A simile is a figure of speech consisting of a comparison using like or as. Well-chosen similes can be used to enliven writing or as an alternative to description using adjectives, for example.

Some similes refer to a universal, or nearly so, quality or attribute of the object of comparison. Examples are:

It is also possible to refer in similes to a characteristic that is possible but not necessary, for example:

Kites are not always being flown, so they are not always high. But flying is what kites are made for and being “up in the sky” is closely associated with them. Even though they are not quite as obvious, such similes are readily understood.

Similes can also be sarcastic:

is not intended to be understood in a straightforward way: it means, in fact, the opposite of what it says.

Some comparisons expressed by similes tend toward the figurative:

has been explained in several different ways — as deriving from the practice of bending back doornails so that they could not be salvaged, or possibly from the use of doornails as early doorknockers, dead to the “abuse” they received as they were knocked. In any case, doornails are not literally dead, having never actually been alive. Another figurative use is

because, technically, dodos aren’t dead, but extinct.

Alliteration may play a role in these as well, because a pattern can certainly be seen:

Similes start off as fresh, interesting language, but like any other phrase, when too often repeated, they become clichés. Most of the color comparisons and animal comparisons have lost their verve: instead of brightening up language, they now make it boring. It’s not enough to sprinkle one’s language with similes to enliven it — it’s also necessary to choose well.