A sonnet is a fourteen-line poem in iambic pentameter with a carefully patterned rhyme scheme. Other strict, short poetic forms occur in English poetry (the sestina, the villanelle, and the haiku, for example), but none has been used so successfully by so many different poets. The Italian, or Petrarchan sonnet, named after Francesco Petrarch (1304-1374), the Italian poet, was introduced into English poetry in the early 16th century by Sir Thomas Wyatt (1503-1542). Its fourteen lines break into an octave (or octet), which usually rhymes abbaabba, but which may sometimes be abbacddc or even (rarely) abababab; and a sestet, which may rhyme xyzxyz or xyxyxy, or any of the multiple variations possible using only two or three rhyme-sounds. The English or Shakespearean sonnet, developed first by Henry Howard, Earl of Surrey (1517-1547), consists of three quatrains and a couplet--that is, it rhymes abab cdcd efef gg.The form into which a poet puts his or her words is always something of which the reader ought to take conscious note. And when poets have chosen to work within such a strict form, that form and its strictures make up part of what they want to say. In other words, the poet is using the structure of the poem as part of the language act: we will find the "meaning" not only in the words, but partly in their pattern as well.The Italian form, in some ways the simpler of the two, usually projects and develops a subject in the octave, then executes a turn at the beginning of the sestet, which means that the sestet must in some way release the tension built up in the octave. (Example: see Wyatt's "Farewell Love and all thy laws for ever.") The Shakespearean sonnet has a wider range of possibilities. One pattern introduces an idea in the first quatrain, complicates it in the second, complicates it still further in the third, and resolves the whole thing in the final epigrammatic couplet. (Example: see Shakespeare's Sonnet 138.) You can see how this form would attract writers of great technical skill who are fascinated with intellectual puzzles and intrigued by the complexity of human emotions, which become especially tangled when it comes to dealing with the sonnet's traditional subjects, love and faith.Although the two types of sonnet may seem quite different, in actual practice they are frequently hard to tell apart. Both forms break between lines eight and nine; the octave in the Italian frequently breaks into two quatrains, like the English; and its sestet frequently ends in a final couplet. In addition, many Shakespearean sonnets seem to have a turn at line nine and another at the final couplet; and if a couplet closes an Italian sonnet, it is usually because the poet wanted the epigrammatic effec t more characterstic of the Shakespearean form. It behooves the reader to pay close attention to line-end punctuation, especially at lines four, eight, and twelve, and to connective words like and, or, but, as,so, if, then, when,or which at the beginnings of lines (especially lines five, nine, and thirteen).十四行诗，又译“商籁体”，为意大利文sonetto，英文Sonnet、法文sonnet 的音译。
欧洲一种格律严谨的抒情诗体。
最初流行于意大利，彼特拉克的创作使其臻于完美，又称“彼特拉克体”，后传到欧洲各国。
由两节四行诗和两节三行诗组成，每行11个音节，韵式为ABBA，ABBA，CDE，CDE或ABBA，ABBA，CDC，CDC。
另一种类型称为“莎士比亚体”（Shakespearean）或“伊丽莎白体”，由三节四行诗和两行对句组成，每行10个音节，韵式为ABAB，CDCD，EFEF，GG。
自欧洲进入文艺复兴时代之后，这种诗体获得广泛的运用。
意大利的诗人彼得拉克成了运用十四行诗体最主要的代表。
他一生写了三百七十五首十四行诗，汇集成《抒情诗集》，献给他的情人劳拉。
在他笔下的十四行诗，每首分成两部分：前一部分由两段四行诗组成，后一部分由两段三行诗组成，即按四、四、三、三编排。
其押韵格式为ABBA，ABBA，CDE，CDE或ABBA，ABBA，CDC，CDC。
每行诗句十一个章节，通常用抑扬格。
彼得拉克的十四行诗形式整齐，音韵优美，以歌颂爱情，表现人文主人思想为主要内容。
他的诗作在内容和形式方面，都为欧洲资产阶级抒情诗的发展开拓了新路。
同时代的意大利诗人和后来其他国家的一些诗人，都曾把彼得拉克的诗作，视为十四行诗的典范，竞相仿效。
因此，人们又称它为彼得拉克诗体。
十六世纪初，十四行诗体传到英国，风行一时，到十六世纪末，十四行诗已成了英国最流行的诗歌体裁。
产生了锡德尼、斯宾塞等著名的十四行诗人。
莎士比亚进一步发展并丰富了这一诗体，一生写下一百五十四首十四行诗。
莎士比亚的诗作，改变了彼得拉克的格式，由三段四行和一副对句组成，即按四、四、四、二编排，其押韵格式为ABAB，CDCD，EFEF，GG。
每行诗句有十个抑扬格音节。
莎士比亚的十四行诗，比彼得拉克更向前迈进一步，主题更为鲜明丰富，思路曲折多变，起承转合运用自如，常常在最后一副对句中点明题意。
后来，弥尔顿、华兹华斯、雪莱、济慈等人也曾写过一些优秀的十四行诗。
英语诗歌的格律1.一首诗（a poem）往往包含有若干诗节（stanze或strophe），每节又分为若干行（line 或verse），每个诗行由若干音步（foot）组成，音步则是由一定数目的重读音节（arsis 或ictus）和非重读音节（thesis）按照一定规律排列而成。
音步的排列方式构成英诗的格律（meter 或measure）。
2.依照每一音步中重读音节（扬）和非重读音节（抑）的排列方式，可以把音步分成不同种类，即格律。
常见的英语诗歌格律有四种。
a)抑扬格（Iambus; the Iambic Foot）：一个音步由一个非重读音节加上一个重读音节构成。
b)扬抑格（Trochee; the Trochaic Foot）：一个音步由一个重读音节加上一个非重读音节构成。
c)扬抑抑格（Dactyl）：一个音步由一个重读音节加上两个非重读音节构成。
d)抑抑扬格（Anapaest; the Anapaestic Foot）：一个音步由两个非重读音节加上一个重读音节构成。
不常见的几种格律。
e)抑扬抑格（Amphibrach; the Amphibrachy Foot）：一个音步由三个音节组成，其中第一、三个音节为非重读音节，第二个音节为重读音节。