An irregular verb is a type of verb that does not follow the standard rules for conjugation in the past tense or past participle forms. Unlike regular verbs, which typically add "-ed" to form these tenses, irregular verbs change their spelling in unpredictable ways. For example, the verb go becomes went in the past tense and gone as a past participle. Irregular verbs are common in the English language and can be challenging for learners. Some well-known examples include be, which changes to was/were in the past tense, and have, which becomes had. Mastering these verbs is essential for effective communication and writing.