Grammar

1. to express purpose.

1.1. Such as:

1.1.1. I’m going to the supermarket to get some fruit

1.2. To express unreal or imaginary situations in the past.

2. First you have to know that the infinitive is the verb in its basic form, meaning it is not in any conjugation and there are no additions such as ing or s or others. And you have to know that the infinitive is of two types 1- preceded by the preposition to and it is called full infinitive 2- not preceded by and called bare infinitive (abstract source)

3. We use the full infinitive (to + base form of the verb):

3.1. When does the complete source mean?

3.1.1. after certain verbs:

3.1.1.1. Such as

3.1.1.1.1. I haven’t managed to find it yet

3.1.1.2. To express remorse

3.1.2. after the objects of certain verbs

3.1.2.1. Such as

3.1.2.1.1. It was Glen who persuaded me to apply for this job.

3.1.2.2. To criticize someone or something.