An Iamb is a type of Foot. A Foot is the basic unit of Accentual-Syllabic meter. Meter basically means structuring a line of poetry in regular and equal units of rhythm. Accentual-Syllabic meter uses both the number of syllables and the location of stressed syllables within a Foot to structure a line. An Iamb is a two-syllable Foot with the stress placed on the 2nd syllable, as in "New York." Notice how the second syllable is stressed more than the first? You can find how words are accented in any dictionary, but it really shouldn't be necessary to go to such trouble; just say them out loud and listen. Often context determines which word or syllable is stressed in a foot, and you need to be aware of how your context might alter the stress in a particular foot. For example, in the sentence "I like your car," car would normally be stressed more than your. However, in "What do you mean your car?" the stress would be placed on your.

A Pentameter is a line of poetry constructed of 5 Feet, or units of rhythm. An Iambic Pentameter then is a line consisting of 5 Iambs, or two syllable Feet with the stress falling on the 2nd syllable of each foot. Or you might say it is a 10-syllable line with the stresses beginning on the 2nd syllable and falling on every other syllable thereafter.

A man who used this form in plays was the
immortal bard. Today you might not tell!
P_I tells me that this was just for no-
-blemen. (Of course you must not split your words!)

The following is written in iams. I suggest you read this node aloud to best discern the rhythm.

There are several types of beats that make up basic rhythm, rhythms used since forms were first transported here to English from its brother languages. French, Italian lines inspired most of Middle English poesy.

If you want to write a rhythmic line you'd use a form with iams, trochees, dactyls, anapests, or even spondees. Iambic lines are oldest, though; they've been in use since the beginning to create heroic couplets, then some sonnets, now blank verse.

If you have a hard time telling when this sort of rhythm is in use, then it's best to draw a diagram of each line that you're reading, where you mark each syllable and accent. If the accents fall on every other syllable then it's likely that you're reading bits of pentameter, iambic.

To create the form yourself it's best to have a bit of background reading works out loud that use the form, like Chaucer's Canterbury Tales (in Middle English), or some of Shakespeare's sonnets. Don't despair; crafting rhythm and a meter takes some difficulty doing.
