Final answer:
Shakespeare used iambic pentameter primarily to mimic natural speech rhythms and to give verse a lyrical, harmonious quality that indicated the speaker's social class. This meter also helped maintain audience focus through its rhythmic and rhetorical qualities.
Step-by-step explanation:
One reason why Shakespeare used iambic pentameter was to mimic natural speech rhythms. This poetic meter, consisting of five sets of iambs per line, was chosen to reflect the intonations and pacing of everyday conversation. Moreover, this meter allowed characters of higher social status to express themselves with a certain lyrical quality, indicating their class. Shakespeare's use of iambic pentameter also made his plays sound more harmonious and poetic.
Aside from mimicking natural speech, iambic pentameter served multiple purposes. It helped signal the literary significance of Shakespeare's work, differentiate between the social classes of characters, and maintain audience focus through its rhythmic quality and the use of rhetoric. Additionally, the structured meter of iambic pentameter necessitated a careful choice of words and phrases, hence sometimes inverting the syntax to fit within the constraints of the meter.