Specifically, it's a linking verb, which connects the subject of a sentence to a predicate nominative or predicate adjective. For example:
* The sky is blue. ("is" connects "sky" to "blue")
* She is a doctor. ("is" connects "she" to "doctor")
Specifically, it's a linking verb, which connects the subject of a sentence to a predicate nominative or predicate adjective. For example:
* The sky is blue. ("is" connects "sky" to "blue")
* She is a doctor. ("is" connects "she" to "doctor")