Infinitive
Infinitive comes in two types: infinitive without to and to-infinitive. Infinitive without to or base infinitive is the base form of a verb. The to-infinitive consists of the word to and the base form of a verb.  
 
Its
When an apostrophe is not used with the word its, it indicates possession. When an apostrophe is used with the word its (it’s), it indicates contraction of it is. Inserting an apostrophe so that it becomes it's when you mean possession makes the sentence wrong grammatically.
 
Without apostrophe
Without an apostrophe, the word its indicates belonging to a noun that has already been mentioned.

 

Examples:

  • The dog is licking its paw.
    (The use of its indicates the paw belongs to the dog.)
  • It flapped its wings and flew off.
  • Their house has its own swimming pool.

 

With apostrophe
With an apostrophe, the word it’s indicates a contraction of it is.

 

Examples:

  • Wrong: Its your turn to make dinner. 

    (The its used here is a contraction of it is. An apostrophe must be used to make the sentence grammatically correct.)

  • Right: It's your turn to make dinner. = It is your turn to make dinner.

 
  • Wrong: Its it's tail that needs washing.

    (The first its is a contraction of it is, an apostrophe must be used. The second its is a possessive form and an apostrophe should not be used.)

  • Right: It's its tail that need washing. = It is its tail that needs washing.