What is the effect of iambic tetrameter (four sets unstressed and stressed syllables) in poem?

Iambic tetrameter is a meter that consists of four iambs, or pairs of unstressed and stressed syllables. It is commonly used in English poetry, particularly in ballads and sonnets. Iambic tetrameter can create a sense of rhythm and regularity in a poem, and it can also help to emphasize certain words or phrases.

For example, in the following line from Shakespeare's "Sonnet 18," the iambic tetrameter helps to create a sense of rhythm and regularity:

> "But thy eternal summer shall not fade"

The line consists of four iambs, with the stressed syllables falling on the first, third, fifth, and seventh syllables. This regular rhythm helps to create a sense of order and balance in the line.

In addition, the iambic tetrameter in this line helps to emphasize the word "eternal." The stressed syllable on the word "eternal" falls on the third syllable, which is the strongest stress in the line. This helps to draw attention to the word "eternal," and it suggests that it is an important concept in the poem.

Overall, iambic tetrameter can be an effective tool for creating rhythm, regularity, and emphasis in poetry. It is a meter that has been used by many poets throughout the centuries, and it continues to be used in contemporary poetry as well.