What is the verb "to be" in English?
The verb "to be" is the most important and most common verb in the English language. It is used to describe identity ("I am a student"), states ("She is happy"), location ("They are at home"), and age ("He is 25 years old"). Unlike other English verbs, "to be" has three present forms (am, is, are) and two past forms (was, were), making it highly irregular.
Identity & Profession
"I am a teacher."
"She is a doctor."
Feelings & States
"They are tired."
"He is hungry."
Location
"We are at school."
"The book is on the table."
Age & Description
"I am 30 years old."
"The house is big."
Key fact: Many languages (Spanish, Arabic, Russian, Chinese) either don't use a "be" verb or use it differently. That's why learners often forget to include it: ✗ "She happy" → ✓ "She is happy".

