Morphology is the branch of linguistics that studies the formation and components of words. Words are built of morphemes, which are the smallest units of language that have meaning. Some morphemes are free; they can stand alone and make sense. Others are bound; they have to be attached to another morpheme. Let's look at the word “walking” as an example. It contains two morphemes: the free “walk” and the bound “ing.” Each of these morphemes has meaning. We know what it means to walk, and when we see the “ing” morpheme, we automatically associate it with the present participle of the verb.
Morphology, then, helps us better understand the functions and meanings of words. Let's see how this works with an example. Pretend you've never seen the word “unusable” before. We can break the word down into three morphemes: “un,” “us” (for “use”), and “able.” The morpheme “use” is familiar, and you know that it means the state of being employed. If you know that the morpheme prefix “un” attaches a negative meaning to a word, and the morpheme suffix “able” indicates that a word is an adjective, you are then able to figure out that “unusable” refers to something that is not fit to be employed or something that is not usable. Since “able” makes the word an adjective, we also know something about the function of the word; it will modify a noun, as in “an unusable computer.”
Morphology also helps us learn the grammar of a language, for many morphemes indicate how words are used grammatically. We already saw this with the example above when we noted that “unusable” is an adjective because of its prefix “able.” We can also see how this works if we look at the common endings of English verbs. We'll take “climb” as our base verb. It is a morpheme in itself, but now let's add some other morphemes to it and conjugate the verb. If we add the morpheme suffix “ed,” we have the past tense “climbed.” If we add the morpheme suffix “ing,” we have the present participle “climbing.” If we add the morpheme suffix “s,” we have the third-person singular present “climbs.” The morphemes we add to the verb tell us how it works grammatically by giving us important information, like tense and number.
Finally, morphology helps us create new words using morphemes we already have in our vocabulary. For instance, the word “google” has become common these days. It is derived from the Google search engine, and it is a verb that means to search the Internet. It acts just like other verbs, so even though it is new, we can add other morphemes to it to create the meanings we want. We can say “googled” when we searched in the past, or “googling” as a present participle, or “he googles” to express what someone is doing right now.