Wiktionary
n. 1 A small book where one writes other people's addresses and phone numbers in. 2 (context computing English) The "Address book" stores contact information (especially e-mail addresses and other data, like postal addresses). It's generally included in http://en.wikipedia.org/wiki/Internet%20suite and http://en.wikipedia.org/wiki/operating%20%20system.
Wikipedia
An address book or a name and address book (NAB) is a book or a database used for storing entries called contacts. Each contact entry usually consists of a few standard fields (for example: first name, last name, company name, address, telephone number, e-mail address, fax number, mobile phone number). Most such systems store the details in alphabetical order of people's names, although in paper-based address books entries can easily end up out of order as the owner inserts details of more individuals or as people move. Many address books use small ring binders that allow adding, removing and shuffling of pages to make room.
Address Book is an address book software application made by Apple that runs on Mac OS X. The Contacts app replaced Address Book in Mac OS X 10.8 ("Lion").
Usage examples of "address book".
When he had finished packing for a week of any weather, loaded his service Beretta, and grabbed his passport, address book, and cell phone, he dressed in his uniform and waited for Kielburger's call with the word from the Pentagon.
The security officer jotted them both down in his electronic address book.
Most hackers do not plan for an arrest by hiding their notes or encrypting their data, and most of them have some sort of address book seized from them too (the most famous of which still remains the one seized from The Not So Humble Babe).