Final answer:
An iamb consists of an unstressed syllable followed by a stressed syllable and is a key element in iambic pentameter, as demonstrated in the poetry of Shakespeare.
Step-by-step explanation:
An iamb is a unit of poetry that consists of an unstressed syllable followed by a stressed syllable. This rhythmical pattern, where each iamb contains one of each type of syllable, is a common element in English poetry and is found in the basic unit of iambic pentameter. An example of iambic pentameter is present in Shakespeare's Sonnet 18, beginning with "Shall I Compare Thee to a Summer's Day?", where each line contains five sets of iambs, equating to about ten syllables per line. The word "forgot" serves as a simple example of an iamb since it naturally follows the alternating unstressed-stressed pattern of an iamb (x /).