In Finnish grammar, the theory of verbs is an essential aspect of understanding the language. Verbs are the most important part of a sentence, as they indicate the action or state of being. Understanding the conjugation and inflection of verbs is crucial for constructing sentences correctly.

Finnish verbs are highly inflected, meaning that they undergo various changes to indicate tense, mood, person, and number. There are six basic tenses in Finnish: present, past, perfect, past perfect, and conditional. Each tense has its own set of conjugation rules, and irregular verbs also exist.

In addition to tense, Finnish verbs can be conjugated according to mood, such as indicative, conditional, imperative, and potential. The potential mood is particularly important in Finnish as it expresses possibility or ability.

Furthermore, Finnish verbs are conjugated based on the person and number of the subject. There are three grammatical persons (first, second, and third) and two numbers (singular and plural). The verb endings change accordingly to match the subject.

Overall, mastering the theory of verbs in Finnish grammar is essential for accurately expressing actions, states, and desires in the language.