The structure and grammatical categories of verbs. Contents introduction chapter I. Theoretical background

1.2. Principles of the structure and grammatical categories of verbs

A grammatical category is a class of units (such as noun and verb) or features (such as number and case) that share a common set of characteristics.

They are the building blocks of language, allowing us to communicate with one another. There are no hard and fast rules for what defines these shared traits, however, making it difficult for linguists to agree on precisely what is and is not a grammatical category.

As the linguist and author R.L. Trask put it, the term category in linguistics

"is so varied that no general definition is possible; in practice, a category is simply any class of related grammatical objects which someone wants to consider."

That said, there are some strategies you can use to group words into categories based on how they function in the English language. (Think of parts of speech.)