Which term describes a form of a verb that usually appears with the word 'to'?

The term that describes a form of a verb typically appearing with the word "to" is "infinitive." In English, the infinitive form of a verb is the base form, often accompanied by "to," such as "to run," "to eat," or "to be." This structure is used to express actions, intentions, or purposes.

It serves various functions in sentences, often acting as a noun, adjective, or adverb. For example, in the sentence "I want to swim," the phrase "to swim" functions as the object of the verb "want," indicating the action the subject desires to perform. Hence, recognizing this structure is essential for understanding verb usage in different contexts.