Verbs are a part of speech that has used to describe an action, state, or occurrence, and forming the main part of the predicate of a sentence, such as hear, become, happen.

Examples of action verbs- sit, stand, talk, walk
Examples of linking verbs- is, are, was, were
Examples of helping verbs- will, would, might, may

For most verbs, you simply add an –ed to go from present tense to past tense. For irregular verbs, the word changes to another word to form the past tense.

Regular verbs just add –ed

Walk-walked   talk-talked       kick-kicked

Irregular verbs change the word

Teach-taught               say-said           buy-bought      catch-caught

You would not say teached, sayed, buyed, or catched.