Conjunctions connect two sentences or clauses.
'Before', 'after', and 'while' are also conjunctions.
'Before' indicates that something happens earlier than something else.
- I want to go to the store before it starts raining.
- Before I took a shower, I cooked dinner.
'After' is the opposite of 'before'. 'After' indicates that an event takes place later than another event.
- I'll go to the store after it stops raining.
'While' tells us that two actions happen at the same time.
- I don't want to go to the store while (= at the same time as) it is raining.