What is the was and were rule in English?

The "was" and "were" rule is about subject-verb agreement in English. It basically means the verb needs to match the subject in its form:

* "Was" is used with singular subjects:

* I was happy.

* She was tired.

* The dog was barking.

* "Were" is used with plural subjects:

* We were excited.

* They were playing.

* The cats were sleeping.

Here's a breakdown:

* Singular subjects are things that are one in number (like "I," "she," "dog").

* Plural subjects are things that are more than one (like "we," "they," "cats").

Tricky situations:

* "You" always takes "were," even though it sounds like a singular pronoun.

* You were right.

* "I" takes "was."

* I was happy.

Important Note: This rule only applies to the past tense of "to be." The present tense uses "am" for "I," "is" for singular subjects, and "are" for plural subjects.