There are mainly three common sentence patterns with if. These are often called the first, second and third conditionals.
In the first conditional, we use a simple present tense in the if-clause and will + infinitive in the result clause.
He will come if you invite him.
In the second conditional, we use a past tense in the if-clause and would + infinitive in the result clause.
He would come if you invited him.
In the third conditional, we use a past perfect tense in the if-clause and would have + past participle in the result clause.
He would have come if you had invited him.
When we are not talking about unreal or imaginary situations, we often use ordinary tenses with if. That means we use past tenses to refer to past time and present tenses to refer to present time.
If you want to win, you have to work hard. (NOT If you want to win, you will work hard.)
If you didn’t study much maths at school, you will find commerce difficult to understand.
Present tense with future meaning
In the if-clause we normally use a present tense to talk about the future.
I will call you, if I have time tomorrow.
In polite requests we often use if + will / would.
If you would fill in this form, I will have your shipment delivered at your home.
