Regular verbs are the ones that follow a pattern when they’re changed to a different person or tense. They have up to 4 different forms: root, third-person singular present (which is usually the same as the root but with the ‑s added at the end), present participle, and past and past participle (which are the same).
Need – needs – needing – needed – needed
Notice how the past and past participle are the same form.
Talk – talks – talking – talked – talked
Call – calls – calling – called – called
Add – adds – adding – added – added
Work – works – working – worked – worked
Present tense regular verbs don’t have ‑s (or ‑es) added to the end of the root word for anything except the third-person singular.
My cat does whatever he wants, not what I want him to do.
They shop at the big market, but he shops at the little one.
Regular verbs also have ‑ed (or ‑d if the verb already ends in ‑e) added to them to change them into past tense.
Laugh – laughed
Push – pushed
Rest – rested