Was and were are “to be” verbs. These auxiliary verbs help express the existence or condition of the subject of the sentence. Knowing when to use was and when to use were can be a tricky concept for native and non-native English speakers alike. Different rules come into play depending on whether you are speaking or writing in the indicative or subjunctive mood.
In the Indicative
The indicative mood is used to make statements of fact and to ask questions. In the indicative, the rules for when to use was and when to use were are simple. Was, was not, and wasn’t are past tense singular; were, were not, and weren’t are past tense plural:
I was bored so I bought a book.
The first person subject pronoun “I” takes a singular verb.
Ginger and Michael were late because of an accident on I-75.
“Ginger and Michael” is a compound subject. Compound nouns are plural, so the subject of this sentence requires a plural verb.
In the Subjunctive
The subjunctive mood is used to express untrue (contrary to fact) conditions and to express wishes. In the subjunctive, were/were not/weren’t should always be used, even when the subject is singular. While was/was not/wasn’t is sometimes used in very informal conversations, it is not grammatically correct:
If I were you, I would enroll in English classes at the English Island in Atlanta. (Formal: grammatically correct)
If I was you, I’d take classes at the English Island. (Informal: grammatically incorrect)
I wish I were better at soccer. (Formal: grammatically correct)
I wish I was better at soccer. (Informal: grammatically incorrect)
Although native English speakers do occasionally use the informal subjunctive “was” in casual speech, you should avoid incorporating this common error into your own conversations. People who use the subjunctive “was” on a regular basis are often judged to be less educated or less intelligent, especially in business situations.