What is the main importance of a passport?

Question

not just the fact that we need one to travel out of the counry but why do we need it to get out of th country

Answer 1

A passport is a formal identity document or certification issued by a national government that identifies the holder as a national of a particular state, and requests permission, in the name of the sovereign or government of the issuing country, for the bearer to be permitted to enter and pass through other countries. Passports are connected with the right of legal protection abroad and the right to enter one's country of nationality. Passports usually contain the holder's photograph, signature, date of birth, nationality, and sometimes other means of individual identification. Many countries are in the process of developing biometric properties for their passports in order to further confirm that the person presenting the passport is the legitimate holder.