Conditional sentences are composed of two clauses, with the first clause introduced by "if" or "unless" expressing a condition that must be met for the second clause to be fulfilled. The verb in the if-clause is always in the present tense even when referring to future conditions, while the main clause uses simple future tense. The order of the if-clause and main clause is not important but the if-clause is always followed by a comma.

1. They are sentences that are formed by two clauses.
One of them, which is introduced by if or unless, expresses a condition
without which the second clause is not fulfilled.
CONDITIONAL SENTENCE
if-clause main clause
If you come home in the afternoon, we will watch a movie on TV.
Unless I finish my homework, I won’t go out on Saturday.
If the water isn’t cold, we will swim in the sea.

2. In real conditions, the action can take place in the future, the verb of the if-
clause is always in present, while the tense of the main-clause is in simple
future.
if-clause main clause
If we water the plants every week, they will grow healthy and beautiful.
Unelss we train really hard, we won’t win our Saturday match.
If the audience isn’t silent, the concert won’t start.
REMARK!!!!
If has a positive meaning unless has a negative one.but

3. The order of the if-clause and the main clause is not important, but when the
if-clause starts, it is always followed by a comma.
If we walk faster, we will arrive at the cinema on time.
They won’t get up early tomorrow unless they switch on the alarm.
Nobody will enjoy the festivals if it doesn’t stop raining.
If I travel to Scotland, I will visit Loch Ness.