What is personification?

Attributing human qualities to something nonhuman.

For example, consider the sentence "The floors groaned."

Floors cannot literally groan. In fact, groaning is generally a human action. Consequently, it can be said that personification is being used, and the purpose for using personification depends on the rhetorical strategy of the specific piece of literature. Any human attribute or action given to something nonhuman, whether its an abstract idea or an inhuman noun, is an example of personification.

Now, that was a random sentence that I arbitrarily made up, so it's not fit for rhetorical analysis. However, in general, adding personification to writing can develop a certain tone, galvanize an audience, and more deeply illustrate a work's theme.