Three distinct types of sonnet exist, each with a different rhyme scheme. Each line in a poem is distinguished by a letter; if two lines have the same letter, the lines rhyme. If two lines have different letters, the lines do not rhyme.
The Shakespearean sonnet uses the rhyme scheme “ABAB CDCD EFEF GG.” The Spenserian sonnet follows a similar, but slightly more complicated rhyme scheme: “ABAB BCBC CDCD EE.” Finally, the Petrarchan sonnet uses the complex rhyme scheme “ABBA ABBA CDCDCD.” Your first attempt at writing a sonnet should be a Shakespearean sonnet. The Shakespearean sonnet's rhyme scheme is flexible and varied, making it the easiest to compose.
Writing lines in iambic pentameter is the most difficult part of writing a sonnet. All sonnets must be written in iambic pentameter, which means that each line in the sonnet has ten syllables, and the syllables alternate in emphasis. The first syllable of a line is not emphasized. The second syllable of a line is emphasized and the third is not. The pattern of non-emphasis and emphasis repeats throughout the entire poem.
The simplest way to determine if your line is iambic is to read it aloud syllable by syllable. When your jaw drops or your throat opens, you are placing emphasis on a syllable. Practice iambic pentameter by reading sonnets written by William Shakespeare or Edmund Spenser, then write lines of your own in iambic pentameter.
All three variations on the sonnet follow the same structure. The first eight lines of a sonnet are called the “octave” and the final six lines are called the “sestet.” The octave of a sonnet is used to present and elaborate on the theme or conflict of the sonnet. The sestet is used to present a resolution or a conclusion.
Somewhere between the seventh and ninth lines of a sonnet, a “turn” occurs that transitions the sonnet from the conflict to the resolution. The turn is usually easy to spot; words like “but,” “yet” and “still” are common indicators of a turn. Write your sonnet with a turn after the octave, and use the last six lines of the poem to bring your work to a conclusion.