Final answer:
The meter of poetry is determined by patterns of stressed and unstressed syllables in a line. Iambic pentameter is five iambs per line, trochaic tetrameter is four trochees, anapestic trimeter is three anapests, and dactylic hexameter is six dactyls. Poets often vary these patterns for effect.
Step-by-step explanation:
To understand the meter of a poem, we first need to look at the syllable patterns in a line. Meter is defined by the sequence of stressed and unstressed syllables, forming different rhythmical units called feet. Each type of foot has a different name, like iamb, trochee, anapest, and dactyl. The number of feet in a line determines the meter's name.
Iambic pentameter is a style of meter featuring five iambs (hence 'penta'), where each iamb is a pair of an unstressed syllable followed by a stressed one, totaling ten syllables per line. An example of iambic pentameter is the line from Shakespeare's Sonnet 18, "Shall I compare thee to a summer's day?"
Trochaic tetrameter consists of four sets (tetrameter) of trochees, where each trochee is a stressed syllable followed by an unstressed one. Anapestic trimeter has three sets (trimeter) of anapests, composed of two unstressed syllables followed by a stressed one. Finally, dactylic hexameter features six (hexameter) dactyls, with each dactyl containing one stressed syllable followed by two unstressed syllables. Dactylic hexameter was famously used in Homer's epic poems, like The Iliad and The Odyssey.
Poets may blend these meters or deviate from them for artistic effect, as Shakespeare often did, such as in the line "To be or not to be: that is the question", where the final syllable extends beyond the standard ten syllables of iambic pentameter. This can create additional emphasis or rhythmical variation within a poem.