A bare infinitive is the same as the base or dictionary form of the verb (e.g., “eat”), while a full infinitive is the base form of the verb preceded by “to” (e.g., “to eat”).
Bare infinitives often follow modal verbs (e.g., “we can fly”), the auxiliary verb “do” (e.g., “don’t touch”), and sense verbs (e.g., “I saw him run”).
There are a few verbs, such as “let” and “make,” that must be followed by bare infinitives instead of full infinitives (e.g., “let me try” not “let me to try”).
Infinitives have many uses, including functioning as subjects, direct objects, adjectives, and adverbs.