In English, we have both regular and irregular verbs.

Regular Versus Irregular:

To form the past tense of a regular verb ending with a vowel (a, e, i, o, u), we add a “d” to the end of the verb. To form the present/past perfect tense, we add a d plus a helping verb (have, had, or has).

An irregular verb is one that does not follow the rules. Some irregular verbs do not change, while others change completely., etc.

For example:
put= present tense
put= past tense
have put=present perfect tense
buy= present tense
bought= past tense
have bought= present perfect tense