A regular verb conforms to a standard set of rules or conventions for conjugating into various tenses. In grammar, conjugating is the changing of the basic form of a verb to represent different inflections, particularly in regards to tense. Most languages have recognized rules for conjugation of verbs, and some languages may have more than one such set, such as French, which has three separate forms of regular verbs, each with its own set of conjugation conventions. By simply identifying a verb as a regular verb, much can be inferred about the constructions of various forms of the verb, if the rules for such constructions in a particular language are known.
In English, the conjugations that determine whether a verb is a regular verb or irregular verb are the past tense and the past participle. The reason for this is that the conjugations for other tenses, such as the present participle or the third person present tense generally do not change, even in irregular verbs, with very few exceptions, such as the verb "to be". In other languages this may or may not be the case.
For a typical regular verb in English, conjugating the past tense or the past participle is done by adding the letters -ed to the present tense, or if the present tense form ends in the letter -e, by simply adding -d at the end of the word. For example, "talk" becomes "talked" and "joke" becomes "joked". Other tenses such as present, past, and future perfect also use the past participle form. The third person plural form of the present tense is the same as the base form, the third person singular form is created by simply adding -s to the base form and the present participle is created by adding -ing to the base form. Using the previous example, "talk" is conjugated into these tenses as "talk," "talks," and "talking".
Conversely, an irregular verb will not follow these rules. Most irregular verbs are learned by native speakers of a language through colloquial usage and at a fairly young age as language skills develop. Sometimes, however, and particularly when learning a second language, a dictionary is needed to find the conjugations of irregular verbs. Most English language dictionaries do not list the conjugations for regular verbs but will list those for irregular verbs.
Occasionally, a regular verb may also be irregular when it has two different meanings. For example, the verb "to hang" can be conjugated in one of two ways, depending on its usage. One of the forms uses a regular conjugation and the other an irregular conjugation. In some cases, certain spellings may be used in the conjugations of more than one verb, but for different tenses. For example, the verb "to ground," is a regular verb, but the verb "to grind," an irregular verb, uses "ground" as its past tense, but with a different meaning.