What Shakespeare Knew About the Rhythms of English
One of the things everyone remembers about Shakespeare, whether they spent a few weeks on one play in high school or an entire semester on several plays in college, is that he wrote in iambic pentameter. Some may also have vague recollections about their teacher explaining that iambic pentameter isn't difficult to understand, because English "naturally" falls into its rhythms. Dismissing iambic pentameter as merely the answer to a trivia question does a disservice to the metrical devices of both Shakespeare and colloquial English. Metrical matters inform not just poetry but the English stress rules that we use every day without being aware of them.
The "pentameter" in "iambic pentameter" refers to the number of units, or poetic feet, in a line of poetry, in this case five feet per line. The "iambic" talks about the structure of those individual units. An iamb is a two-syllable foot, an unstressed syllable followed by a stressed syllable. Iambs are based on syllables, not words, so they can cross word boundaries. Thus, iambic [entameter is five unstressed/stressed units in a row, which make up one line. This is the pattern that Shakespeare used most often in his poetry, but it should be noted that there are several other metrical patterns mixed in.