Here's why:
* Course titles are proper nouns: They are specific names for particular courses, similar to the way we capitalize names of books or movies.
* Capitalization for clarity: Capitalization helps distinguish the course name from general concepts. For example, "Grammar" in a course title refers specifically to that course, whereas "grammar" in general refers to the rules of language.
Examples:
* Introduction to Linguistics
* Phonetics and Phonology
* Advanced Grammar
However, if you are referring to the general concepts outside of a course title, they wouldn't be capitalized:
* "I'm interested in learning more about grammar."
* "Phonetics is the study of speech sounds."
* "Linguistics is a fascinating field."