What part of speech is am and was?

"Am" and "was" are both verbs. More specifically, they are auxiliary verbs, also known as helping verbs.

Here's why:

* They help form verb tenses: "Am" helps form the present tense of the verb "to be" (e.g., "I am happy"). "Was" helps form the past tense of the verb "to be" (e.g., "She was tired").

* They don't act as main verbs on their own: They need another verb to complete the sentence.

Let me know if you'd like more examples or have other grammar questions!