As long as, provided, providing

As long as, provided and providing are subordinating conjunctions. They express condition and are used at the beginning of a subordinate clause.

As long as

We use as long as to express a condition, i.e. to say that something will happen only on condition that something else happens.

I'll lend you the book as long as you promise to give me it back next week.
(= If you don't promise to give the book back next week, I will not lend you it.)

As long as expresses that one thing depends on another.

You can go to the party as long as you come back before midnight.
(= You can go to the party, but you must promise to be back before midnight.)

As long as has the same meaning as if, providing and provided.

You can go to the party if/providing/provided you come back before midnight.

We're going skiing next week if/providing/provided there's enough snow.