There are variations in the way verbs form the past tense. They can be looked at in the following way: ...

Some past participles are irregular. For example ... Have a look at the regular verbs in the perfect tense guide to find out when to use the perfect tense and how to form it with regular verbs.

A regular verb is one that conforms to the rules of grammar, whereas an irregular verb is one that does not ... but the most common one you will use besides the present tense will be the past tense.