Answer:
Adjectives a words used to describe, modify or name an attribute of a noun or noun phrase. They can also be used to describe the quantity of nouns. Depending on their use, there can be numbers, interrogative, indefinite, coordinate, demonstrative, possessive or attributive adjectives. This last classification would be the one including those adjectives used to describe our favourite song.
Memorable, epic and inspiring would be three adjectives that could easily describe any person's favourite song.