What is the poetry technique where every second syllable is accented?

Answer 1

Short answer: the iambic foot.

Your intention seems clear, but the question isn't the best way to express it. The iambic foot consists of two syllables, the second one accented. If a poet is writing in iambic pentameter, this means that each line is made up of five iambic feet. This is the structure that Shakespeare used in almost all of his work. However, poets are rarely locked in to this kind of structure; even Shakespeare took many liberties. Slavish devotion to this kind of formal structure often results in doggerel, much like greeting card poems or beginners' attempts at verse. You can often tell when this is happening because writers will seriously strain the flow of the language itself in order to maintain the sing-song da-DA, da-DA, da-DA, da-DA, da-DA rhythm. They think that forcing language into this pattern means that they have written good verse. Better poets consider the prosody (flow and rhythm) of language, and discover, uncover or create language whose rhythms naturally follow a certain kind of arch. That is the kind of language they include in their verse. When you encounter a line of superb iambic verse, it might take more than one reading to realize it is iambic. The rhythm should not get in the way.

Keep in mind that this rhythmic analysis, [the different kinds of poetic feet and the ways that they are used in verse] along with all its variations, comes from the analysis of classical Greek verse. For centuries it was considered necessary to form English verse using the same kinds of rhythmic structures. While these structures accommodate Greek verse extremely well, they are more challenging when applied to English for a variety of reasons.