Iambic pentameter

Iambic pentameter is a meter in poetry, consisting of an unrhymed line with five iambs or feet (hence pentameter), felt by many to be the most powerful of all metrical forms in English poetry. Shakespeare excelled in the use of iambic pentameter (as in his famous Sonnet XVIII, beginning "Shall I compare thee to a summer's day"). And consider this from Christopher Marlowe's "Dr Faustus":

Was this the face that launch'd a thousand ships,
And burnt the topless towers of Ilium?

When read aloud such verse naturally follows a beat, alike to that of a human heart beat at rest. In written form it looks like this:

da-dum da-dum da-dum da-dum da-dum

So Marlowe's work would follow the pattern:

Was-this  the-face  that-launch'd  a-thou  sand-ships

And-burnt  the-top  less-towers  of-Il  i-um?

There is some debate over whether works such as Shakespeare's and Marlowe's were originally performed with this rhythm prominent, or whether it was disguised by the patterns of normal speech as is common today.