Adjectives add information to or describe a noun.

• Comparative forms end in -er or are preceded by “more”.
• Superlatives end in -est or are preceded by “the most”.
• Compound adjectives are formed by 2 or more adjectives together: bright blue.
• Other word classes can be used as adjectives, e.g. nouns (boyfriend jeans); perfective verbs (frightened tourists); progressive verbs (infuriating sister).

There are also ways of describing different kinds of adjective semantically, i.e. according to their meaning:

• Descriptive adjectives simply provide information: the thin boy
• Evaluative adjectives describe things in a way that also provides a judgement about them (this can be negative or positive): the gangly boy
• Emotive adjectives are intended to provoke an emotional reaction from the audience: the anorexic-looking boy

Note that it is often possible to describe the same adjective as ‘evaluative’ and ‘emotive’.  That’s the problem with semantic categories - we may all react slightly differently to the same words.  Don’t spend too long wondering whether a word is ‘evaluative’ or ‘emotive’ - just pick one! (and justify it in your analytical comment).