information on the sonnet

http://en.wikipedia.org/wiki/Sonnet
The term "sonnet" derives from the Occitan word sonet and the Italian word sonetto, both meaning "little song." It had come to signify a poem of fourteen lines that follows a strict rhyme scheme and specific structure. One of the best-known sonnet writers is Shakespeare, who wrote 157 sonnets. Traditionally, when writing sonnets, English poets usually employ iambic pentameter.

http://en.wikipedia.org/wiki/Shakespeare's_sonnets#Structure
The sonnets are each constructed from three four-line stanzas (called quatrains) and a final couplet composed in iambic pentameter[7] (a meter used extensively in Shakespeare's plays) with the rhyme scheme abab cdcd efef gg (this form is now known as the Shakespearean sonnet).

http://en.wikipedia.org/wiki/Petrarchan
Original Italian sonnet form in which the sonnet's rhyme scheme divides the poem's 14 lines into two parts, an octave (first eight lines) and a sestet (last six lines). The rhyme scheme for the octave is typically abbaabba. There are a few possibilities for the sestet, including cdecde, cdcdcd, and cdcdee. The Petrarchan Sonnet consists of many rhymed lines, more than any other sonnet. This is much easier to accomplish in Italian, a language more rich in rhyming words, than in English. The first eight lines create an octave, with the rhyme scheme a b b a a b b a. The last six lines make up a sestet and may consist of following rhyme schemes: 1) c d e c d e 2) c d e d c e 3) c d c d c d.