国际象棋的最初阶段称为“开局”。刚开始的几个回合棋手主要关心自己的棋子是否从起始点移动到有利的位置。游戏的初期，白方发动的一连串经过检验的步法称为“开局”，而黑方回应的步法称为“防御”。为人熟知的开局走法有好几十种，而其中又有好几百种被赋予名称的变著。《牛津国际象棋大辞典》列出了1,327有名称的开局与变著[1]，从平和的局面型走法，到激烈的战术型走法通通包括在内。
| a | b | c | d | e | f | g | h | |
| 8 | | 8 |
| 7 | 7 |
| 6 | 6 |
| 5 | 5 |
| 4 | 4 |
| 3 | 3 |
| 2 | 2 |
| 1 | 1 |
| a | b | c | d | e | f | g | h | |
国际象棋的起始局面
一连串正规的步法称为“开局步法”，一些工具书如《国际象棋开局百科》有对开局步法做了编目索引。这些工具书通常利用代数记谱法、开局树状图、或开局理论表将一连串的步法呈现给读者。如果开局偏离了“开局步法”，之后的变化就称为“out of book”。某些开局的主线已研究到20到25步之多。有一些甚至还分析到了第30或35步，像是古印度防御、西西里防御中的舍文宁根变著、以及纳依道夫变著。职业棋手们花费数年的时间来研究开局，而随著开局理论不断演进，许多棋手甚至终其一生都在研究开局。
开局中创新的走法称为“创新理论”。有些棋手会保留这种创新的走法，直到正式比赛时才施展出来，这就叫做“预备变著”，在高等级比赛中通常会有意想不到的效果。开局分类可参见国际象棋开局列表。
这是按照《国际象棋开局百科》（ECO）中的编号整理的国际象棋开局列表。1966年国际象棋通报将国际象棋开局分为五个大类（A到E），每大类细分为一百个小类（00到99），出版为五卷本，每卷分别标为“A”到“E”。以下是ECO分类法的国际象棋开局列表。
详情参照:西洋棋开局列表
开局方法千变万化，但会有几个常见的目标[2]：让棋子到可以影响棋局的位置、控制中心、保护国王的安全、避免兵出现弱势、棋子适当的调度、创造比对手有利的优势。
第一，在高等级的比赛中，白方开局的目标通常是以保持优势为主，而黑方的目标则是以消除白方优势为主。因为白方有先行的优势，假如黑方刻意模仿白方走子，白方永远会比黑方早一步攻击。
第二，自从1950年开始，另一个开局目标逐渐受到重视。根据国际大师Jeremy Silman的观点，开局的目标是制造双方的不平衡，这种不平衡进而影响到中局的情势及棋手的进攻计画。
第三个目标则是用来辅助前两个目标，那就是将局面诱导到自己熟悉且偏爱的布局，这通常是靠颠倒行棋顺序来达到目的。
Hooper, David; Whyld, Kenneth. The Oxford Companion to Chess 2. Oxford University Press. 1992: 461–480. ISBN 0-19-280049-3.
- Nick de Firmian is a three-time U.S. Chess Champion. Often called "MCO-14" or simply "MCO", this is the 14th edition of the work that has been the standard English language reference on chess openings for a century. This book is not suitable for beginners, but it is a valuable reference for club and tournament players.
- Garry Kasparov is the former World Chess Champion from 1985 to 2000 and Raymond Keene is a former British chess champion. This book is often called "BCO 2" and is intended as a reference for club and tournament players.
- John Nunn is a former British Chess Champion and a noted chess author. This book is often called "NCO" and is a reference for club and tournament players.
- Sahovski Informator. Encyclopaedia of Chess Openings
- This is an advanced, technical work in five volumes published by Chess Informant of Belgrade. http://www.sahovski.com/（页面存档备份，存于互联网档案馆） It analyzes openings used in tournament play and archived in Chess Informant since 1966. Instead of using the traditional names for the openings and descriptive text to evaluate positions, Informator has developed a unique coding system that is language independent so that it can be read by chess players around the world without requiring translation. Called the "ECO", these volumes are the most comprehensive reference for professional and serious tournament players.
- Scheerer, Christoph. The Greatest Ever Chess Opening Ideas. Everyman Chess. 2008. ISBN 978-1-85744-561-9.
- Seirawan, Yasser. Winning Chess Openings. Everyman Chess. 2003. ISBN 1-85744-349-7. An elementary/introductory book.
- Stefan Djuric, Dimitri Komarov, & Claudio Pantaleoni, Chess Opening Essentials (4 volumes)
- Summerscale, Aaron. A Killer Chess Opening Repertoire. Globe Pequot. 1999. ISBN 978-1-85744-519-0.
- van der Sterren, Paul, Fundamental Chess Openings, Gambit, 2009, ISBN 978-1-906454-13-5
- Ward, Chris. The Queen's Gambit Accepted. Batsford. 1999. ISBN 0-7134-8467-5.
- Watson, John. Mastering the Chess Openings 1. Gambit. 2006. ISBN 978-1-904600-60-2. (Three chapters of general opening principles; open and semi-open games)
- Watson, John. Mastering the Chess Openings 2. Gambit. 2007. ISBN 978-1-904600-69-5. (Closed games and Indian defenses)
- Watson, John. Mastering the Chess Openings 3. Gambit. 2008. ISBN 978-1-904600-98-5. (English Opening)
- Watson, John. Mastering the Chess Openings 4. Gambit. 2010. ISBN 978-1-906454-19-7.
