Phonology, syntax, and semantics are three important areas of study in linguistics. Phonology is all about the sounds of a language. Remember the lyrics of that old song, “You say to-mā-to; I say to-mah-to”? A phonologist is interested in how and why the two vowel sounds differ among various groups of people.
Let's look at another example. In Old English (spoken in England from about the mid-fifth century through the eleventh century), words that look much the same as those of modern English were actually pronounced quite differently. The Old English word “wē” means the same as the modern “we,” but it was pronounced like “way” rather than “wee.”
Phonologists study sounds like these, how each language combines them to form words, and how they change over time. Books of phonology, or sections of language books that deal with phonology, often list the vowels and consonants of a language, explain how they are pronounced in various situations, and sometimes explore how they developed over time.
Syntax is the study of how words are combined into phrases and sentences and how they function in a phrase or sentence. For instance, each language has rules about the proper order of words and phrases. English is quite strict in most cases, for it typically forms sentences with a subject-verb-object order like this: Mary bought groceries. We would think it quite odd if someone said, “Groceries Mary bought” (although we might think that the speaker wants to place some special emphasis on groceries), and no one would remark that “Groceries bought Mary”!
Other languages, however, allow for a more flexible syntax. Latin, for example, relies less upon word order and more upon endings that show a word's function in a sentence. In Latin we can say, “Marcus videt urbem” (Mark sees a city) or “Urbem Marcus videt” or even “Urbem videt Marcus,” and the meaning remains the same, for “urbem” is always the direct object form of the noun “urbs” no matter where it is located in the sentence, and Marcus is always the subject form.
While phonology focuses on sounds and syntax on structures, semantics concentrates on meanings. Scholars who study semantics look closely at the meanings of words, how languages use those words literally and figuratively, and how meanings change over time. What do we think of when we hear the word “doom”? Something negative, right? The idea of someone going to his doom is certainly not a pleasant one.
In Old English, however, the word “dōm” could mean “doom” in a modern sense but could also refer to a judgment either positive or negative or even the glory that results from a positive judgment. The word's meaning was much broader. Semantics explores those meanings, the changes in their range over the centuries, and the reasons behind the changes.
Semantics also studies how language is used figuratively. Think of all the different meanings a person can attach to the word “fine.” Literally, it means that something is good or acceptable, but figuratively, people can use it to mean the exact opposite. Imagine you are upset with a friend and yell, “Fine!” as you are walking out of the room and slamming the door behind you. You certainly don't mean that all is well; you just mean you want to end the argument for now. Semantics identifies and examines these kinds of non-literal (in this case, ironic) meanings.