BOTSFORD, J.

In 2011, Melissa Tyler, a customer of Michaels Stores, Inc. (Michaels), filed an action on behalf of herself and a putative class of Michaels customers in the United States District Court for the District of Massachusetts. Tyler's complaint alleged that Michaels unlawfully writes customers' personal identification information on credit card transaction forms in violation of G. L. c. 93, § 105 (a) (§ 105 [a]), when Michaels's employees request and record customers' zip codes in processing credit card transactions.1 A judge of the United States District Court for the District of Massachusetts certified the following questions to this court pursuant to S.J.C. Rule 1:03, as appearing in 382 Mass. 700 (1981):

We answer "Yes" to the first question, but for different reasons than the judge set forth in the question itself. We also answer "Yes" to the second and third questions.

Background. Tyler's complaint alleges the following facts that we accept as true for the purposes of answering the certified questions. On several occasions during the past year, Tyler made purchases with a credit card at a Michaels retail store in Everett. During these transactions, a Michaels employee asked Tyler to provide her zip code. Tyler disclosed the number under the mistaken impression that she was required to do so in order to complete the credit card transaction, but in fact, the credit card issuer did not require Michaels to request zip codes. Michaels maintains a policy of writing customers' names, credit card numbers, and zip codes on electronic credit card transaction forms in connection with credit card purchases. Michaels used Tyler's name and zip code in conjunction with other commercially available databases to find her address and telephone number. Tyler subsequently received unsolicited and unwanted marketing material from Michaels.

Tyler filed her class action complaint against Michaels on May 23, 2011, claiming that Michaels's electronic recording of customer zip codes amounts to writing personal identification information on a credit card transaction form in violation of § 105 (a) and therefore constitutes an unfair or deceptive act or practice as defined in G. L. c. 93A, § 2. The complaint also contains a claim for unjust enrichment and seeks a declaratory judgment that Michaels's collection of zip codes violates § 105 (a). Michaels filed a motion to dismiss the complaint on July 22, 2011. On January 6, 2012, the District Court judge granted the motion. The judge concluded that (1) Tyler sufficiently alleged a violation of § 105 (a) because zip codes constitute personal identification information,2 and Michaels's electronic credit card terminal may contain "credit card transaction form[s]" within the meaning of § 105 (a); but (2) the complaint failed to allege that Michaels's collection of zip codes caused Tyler an injury cognizable under G. L. c. 93A. The judge also concluded that the complaint failed to state a claim for unjust enrichment and that Tyler was not entitled to the declaratory relief she sought. At the invitation of the judge, on January 13, 2012, Tyler filed a motion to certify certain questions concerning the proper interpretation of § 105 (a) to this court. The judge certified the three questions set forth supra.

Discussion. All three questions turn on the meaning and purpose of § 105 (a), and G. L. c. 93, § 105 (§ 105), more generally. It is therefore useful to identify the purpose or purposes of these statutory provisions at the outset.

Section 105 (a) provides:

Section 105 (d) states that "[a]ny violation of the provisions of this chapter shall be deemed to be an unfair and deceptive trade practice, as defined in section 2 of chapter 93A." Thus, a violation of § 105 (a) is unlawful under G. L. c. 93A, § 2,3 and may be the basis for a claim under c. 93A, § 9.4

The judge opined that the main purpose of § 105 (a) is to prevent identity fraud and not, as Tyler contends, to protect consumer privacy. Michaels advances the same interpretation of the statute as the judge. We disagree for three reasons.

First, keeping in mind the rule that the actual words chosen by the Legislature are critical to the task of statutory interpretation,5 there is nothing in the actual language of § 105 (a) to suggest that its purpose is confined to preventing identity fraud. Rather, by its inclusive terms § 105 (a) reflects concern about, and an intent to limit, disclosure of personal information leading to the identification of a particular consumer generally.

Thus, § 105 (a) expressly "applies to all credit card transactions" and delineates a general prohibition that "[n]o person, firm, partnership, corporation or other business entity ... shall write, cause to be written or require that a credit card holder write personal identification information, not required by the credit card issuer, on the credit card transaction form" (emphases supplied). The statute also defines "[p]ersonal identification information" in a nonexclusive manner, stating that the term "shall include, but shall not be limited to, a credit card holder's address or telephone number." Id. We discern nothing in these expansive and general terms that indicates or suggests that prevention of identity fraud was the single point of legislative focus.

Second, and contrary to the District Court judge, we find the title of § 105 to offer useful guidance. See, e.g., American Family Life Assur. Co. v. Commissioner of Ins. 388 Mass. 468, 474, cert. denied, 464 U.S. 850 (1983), and cases cited ("although the title of an act cannot control the plain provisions of the act, it may aid construction of ambiguous clauses"). Section 105 was inserted in the General Laws by St. 1991, c. 414, § 1. The title of this act is "An Act relative to consumer privacy in commercial transactions." The significance of this title gains strength from the fact that in the text itself, the Legislature inserted a caption into the General Laws for this new legislation. Thus, St. 1991, c. 414, § 1, begins: "Chapter 93 of the General Laws is hereby amended by adding under the caption `CONSUMER PRIVACY IN COMMERCIAL TRANSACTIONS,' the following two sections: [§§ 1046 and 105]." Both title and caption thus expressly reference "consumer privacy in commercial transactions," reinforcing the view that the Legislature indeed was concerned, as Tyler suggests, about privacy issues in the realm of commercial dealings and in any event was not necessarily focused solely on preventing identity fraud.

The third reason for our disagreement relates to the legislative history of § 105. See Commonwealth v. Welch, 444 Mass. 80, 85 (2005), rev'd on other grounds, O'Brien v. Borowski, 461 Mass. 415, 425 (2012) (although "[o]ur starting point is... the plain language of the statute, ... we also seek guidance from its legislative history"). As detailed in the following paragraph, this history strongly suggests that there were at least two privacy-related purposes underlying § 105: credit card identity fraud and consumer privacy.

The legislation that ultimately was enacted as § 105 in December of 1991 was introduced by Senator Lois Pines and then Representative Suzanne Bump. See 1991 Senate Doc. No. 89; 1991 Senate Doc. No. 1510; 1991 House Doc. No. 6112. The legislative record pertaining to this legislation includes a memorandum specifically prepared in March, 1990, for Senator Pines by the Boston University Legislative Services, entitled "A Bill regulating check cashing and credit card acceptance procedures" (Pines memorandum) and a report prepared in November, 1990, by the Massachusetts Public Interest Research Group (MASSPIRG), entitled "What They Know Can Hurt You: A Survey of Retail Merchant Check Cashing and Credit Card Policies" (MASSPIRG report). The Pines memorandum describes the need for, and contains a preliminary draft of, the text of what became 1991 Senate Doc. No. 89, a bill introduced by Senator Pines that served as the principal predecessor to 1991 Senate Doc. No. 1510. See Pines memorandum, supra at 2-7, 38. The 1991 Senate Doc. No. 1510, in turn, was enacted as St. 1991, c. 414.7 These documents indicate that the proposed legislation had two distinct goals: for check transactions (now covered in § 105 [b]8), the goal or purpose was to prohibit recording of credit card information on checks to prevent misuse and credit card fraud;9 and for credit card transactions (now covered in § 105 [a]), the purpose was to safeguard consumer privacy and more particularly to protect consumers using credit cards from becoming the recipients of unwanted commercial solicitations from merchants with access to their identifying information.10 Additional evidence of the Legislature's dual purpose in creating § 105 may be derived from Governor Weld's papers concerning 1991 Senate Doc. No. 1510, which contain an October, 1991, memorandum from the Executive Office of Consumer Affairs (Consumer Affairs memorandum), and a December, 1991, memorandum from the Governor's deputy legal counsel (Governor's memorandum). They explain that the objective of 1991 Senate Doc. No. 1510 "is to protect consumers' privacy and protect them from fraud." Consumer Affairs memorandum, supra at 1. Governor's memorandum, supra at 2.

To summarize: based on the text, title and caption, and legislative history of § 105, we are persuaded that the principal purpose of § 105 (a), in contrast to § 105 (b), is to guard consumer privacy in credit card transactions, not to protect against credit card identity fraud.11 Against this backdrop, we now turn to the three certified questions.

1. Meaning of "personal identification information." The first certified question asks whether a zip code is "[p]ersonal identification information" under § 105 (a).12 The statute defines "personal identification information" as including, but not limited to, "a credit card holder's address or telephone number." G. L. c. 93, § 105 (a). As indicated previously, this definition is explicitly nonexhaustive. Although a cardholder's address and telephone number unquestionably constitute personal identification information, the definition leaves open the possibility that other information may also so qualify. Tyler contends that because a zip code is part of an address, and § 105 (a) defines a cardholder's address as personal identification information, the zip code automatically qualifies as personal identification information as well.13 Even if we agree with Michaels that this deductive reasoning fails, we still conclude that a zip code may well qualify as personal identification information under § 105 (a). This is so because, according to (and accepting for present purposes) the allegations of the complaint, a consumer's zip code, when combined with the consumer's name, provides the merchant with enough information to identify through publicly available databases the consumer's address or telephone number, the very information § 105 (a) expressly identifies as personal identification information. In other words, to conclude in those circumstances that zip codes are not "personal identification information" under the statute would render hollow the statute's explicit prohibition on the collection of customer addresses and telephone numbers, and undermine the statutory purpose of consumer protection. See Adamowicz v. Ipswich, 395 Mass. 757, 760 (1985), quoting Lexington v. Bedford, 378 Mass. 562, 570 (1979) ("The construction of a statute which leads to a determination that a piece of legislation is ineffective will not be adopted if the statutory language is `fairly susceptible to a construction that would lead to a logical and sensible result'").

2. Requirements for bringing an action under § 105 (a). The second question asks whether a plaintiff may bring an action for a violation of § 105 (a) absent identity fraud. We see no reason to read into the statute a requirement that one be the victim of identity fraud in order to assert a claim under that statute. It does not contain an express limitation to that effect, and as previously discussed, we interpret § 105 (a) itself as being intended primarily to address invasion of consumer privacy by merchants, not identity fraud. The achievement of this purpose would be hindered rather than advanced by imposing a requirement that the plaintiff be a victim of identity fraud in order to raise a claim of statutory violation. See Commonwealth v. De'Amicis, 450 Mass. 271, 276 (2007), quoting Hanlon v. Rollins, 286 Mass. 444, 447 (1934) ("a statute must be interpreted according to the intent of the Legislature ascertained from all its words ... considered in connection with the cause of its enactment, the mischief or imperfection to be remedied and the main object to be accomplished").

Accordingly, our direct answer to the second question is that a plaintiff may bring an action for a violation of § 105 (a) without alleging a claim of identity fraud. We accept the judge's invitation to expand on this answer, however, and consider briefly the issue of what must be alleged in such an action with respect to injury or loss.

Because § 105 (d) provides that a violation of § 105 (a) "shall be deemed to be an unfair and deceptive trade practice, as defined in [G. L. c. 93A, § 2]," a consumer seeking to bring an action for a violation of this statute would do so pursuant to G. L. c. 93A, § 9(1), as Tyler has done in this case. A complaint under G. L. c. 93A, § 9(1), see note 4, supra, must allege that the plaintiff has been "injured" by the act or practice claimed to be unfair or deceptive and therefore unlawful under c. 93A, § 2. Tyler relies on Leardi v. Brown, 394 Mass. 151 (1985) (Leardi), and argues that a violation of § 105 (a) directly equates with an injury under c. 93A, § 9(1), and therefore, a complaint alleging a violation of § 105 (a), without more, satisfies the injury requirement of c. 93A, § 9, and entitles the plaintiff to recover damages, nominal or otherwise.

The Leardi case considered an amendment to G. L. c. 93A, § 9, that eliminated the requirement that one suffer a "loss of money or property" in order to be "injured" within the meaning of c. 93A, § 9(1), as appearing in St. 1979, c. 406, § 1.14 See Leardi, 394 Mass. at 158. This court's decision in Leardi has been a source of some confusion in the years since 1985. The confusion appears to stem from the following language:

Id. at 160. Later decisions of this court have interpreted the Leardi case and the language quoted here in different ways.15 Nevertheless, our recent decisions generally establish the following. The invasion of a consumer's legal right (a right, for example, established by statute or regulation), without more, may be a violation of G. L. c. 93A, § 2, and even a per se violation of § 2, but the fact that there is such a violation does not necessarily mean the consumer has suffered an injury or a loss entitling her to at least nominal damages and attorney's fees; instead, the violation of the legal right that has created the unfair or deceptive act or practice must cause the consumer some kind of separate, identifiable harm arising from the violation itself.16 See Rhodes v. AIG Dom. Claims, Inc., 461 Mass. 486, 496 n.16 (2012) (Rhodes); Casavant v. Norwegian Cruise Line Ltd., 460 Mass. 500, 504-505 (2011) (Casavant); Iannacchino v. Ford Motor Co., 451 Mass. 623, 632-633 (2008) (Iannacchino); Hershenow v. Enterprise Rent-A-Car Co. of Boston, 445 Mass. 790, 801-802 (2006) (Hershenow). To the extent that the quoted passage from Leardi can be read to signify that "invasion" of a consumer plaintiff's established legal right in a manner that qualifies as an unfair or deceptive act under G. L. c. 93A, § 2, automatically entitles the plaintiff to at least nominal damages (and attorney's fees), we do not follow the Leardi decision. Rather, as the Rhodes, Casavant, Iannacchino, and Hershenow decisions indicate, a plaintiff bringing an action for damages under c. 93A, § 9, must allege and ultimately prove that she has, as a result, suffered a distinct injury or harm that arises from the claimed unfair or deceptive act itself.17

Returning to § 105 (a), there appear to be at least two types of injury or harm that might in theory be caused by a merchant's violation of the statute: the actual receipt by a consumer of unwanted marketing materials as a result of the merchant's unlawful collection of the consumer's personal identification information;18 and the merchant's sale of a customer's personal identification information or the data obtained from that information to a third party.19 When a merchant acquires personal identification information in violation of § 105 (a) and uses the information for its own business purposes, whether by sending the customer unwanted marketing materials or by selling the information for a profit, the merchant has caused the consumer an injury that is distinct from the statutory violation itself and cognizable under G. L. c. 93A, § 9.20

3. Meaning of "credit card transaction form." The third question asks whether the term "credit card transaction form" in § 105 (a) should be understood to refer equally to electronic and paper transaction forms.21

Section 105 (a) provides that "[n]o person ... or ... business entity that accepts a credit card for a business transaction shall write, cause to be written or require that a credit card holder write personal identification information ... on the credit card transaction form." G. L. c. 93, § 105 (a). The section affirmatively declares that its provisions "shall apply to all credit card transactions" (emphasis supplied), and it contains no language expressly limiting a "credit card transaction form" to a paper form. Accordingly, as noted by the judge, the language of § 105 (a) naturally appears to include all such transactions, whether they are processed manually or electronically. The reference to the verb "write" in § 105 (a) does not foreclose such an interpretation because by definition, the verb encompasses inscriptions made by hand and by typing. Webster's Third New International Dictionary 2640-2641 (1993) (defining "write" to include "to form or produce [a legible character] in, upon, or by means of a suitable medium," "to produce [symbols or words] by machine," and "to form or produce letters, words, or sentences with a pen, pencil, or machine"). See Allen v. Boston Redev. Auth., 450 Mass. 242, 256 (2007) ("Where a statutory term is not defined, it must be understood in accordance with its generally accepted plain meaning"); G. L. c. 4, § 6, Third ("Words and phrases shall be construed according to the common and approved usage of the language"). Based on the words chosen by the Legislature, therefore, we interpret "credit card transaction form" to apply to transactions involving both electronic and paper forms.22

There are other reasons to reject a narrow interpretation of the statutory language advocated by Michaels. To construe § 105 (a) as inapplicable to electronic credit card transactions would render the statute essentially obsolete in a world where paper credit card transactions are a rapidly vanishing event. See EMC Corp. v. Commissioner of Revenue, 433 Mass. 568, 570 (2001), quoting Pacific Wool Growers v. Commissioner of Corps. & Taxation, 305 Mass. 197, 199 (1940) ("statutes are to be interpreted ... in connection with ... the history of the times... contemporary customs and conditions and the system of positive law of which they are part"). Such a construction would thus fail to carry out the statutory purpose of protecting consumer privacy because it would allow merchants to avoid the statute's prohibition against collecting personal identification information simply by using electronic means to capture and reflect any electronic credit card transaction. Where possible, a statute should not be interpreted to render it ineffective. See Adamowicz v. Ipswich, 395 Mass. 757, 760 (1985), quoting Lexington v. Bedford, 378 Mass. 562, 570 (1979).

Conclusion. As to the first certified question, we respond that a zip code constitutes personal identification information for the purposes of G. L. c. 93, § 105 (a). As to the second certified question, we respond that a plaintiff may bring an action for violation of G. L. c. 93, § 105 (a), absent identity fraud. As to the third certified question, we respond that the term "credit card transaction form" in G. L. c. 93, § 105 (a), refers equally to electronic and paper transaction forms.

The Reporter of Decisions is directed to furnish attested copies of this opinion to the clerk of this court. The clerk in turn will transmit one copy, under the seal of the court, to the clerk of the United States District Court for the District of Massachusetts, as the answer to the questions certified, and will also transmit a copy to the parties.