Team is or team are?

Should it be "The team is" or "The team are"?

Well, both are acceptable and the choice depends on how the group word team is viewed.

Like family, jury, choir and committee, the word team is a collective noun. Unlike a common countable noun such as boy or table, which always requires a singular verb in the present tense, a collective noun can be used with either a singular or plural verb:

(1) Our team hopes to win the championship.
(2) Our team hope to win the championship.

In sentence (1), the word team is conceived as one entity and takes the singular verb hopes. In sentence (2), the same word is viewed as a group of people and so takes a plural verb with no inflection.

All collective nouns that name groups of members can usually be treated the same way. "Usually" because sometimes only the singular sense of the collective noun is possible. Sentence (3) below, where the group is being considered as a unit, illustrates this singular use (Quirk et al. 216):

(3) The audience was enormous.

Applying the plural sense of audience to sentence (3) would lead to an awkward sentence:

(4) ?The audience were enormous.

Whether we treat collective nouns as singular or plural, it is important to be consistent:

5) The committee has submitted its plan.
6) The committee have submitted their plan.

If we intend to use committee in the singular sense, then our choice of the singular verb has should match the singular possessive pronoun its.

However, if we choose the plural meaning of committee accompanied by the plural have, we should correspondingly use the plural their.

Inconsistency in the treatment of collective nouns can result in grammatically odd sentences:

(7) ?The committee has submitted their plan.
(8) ?The committee have submitted its plan.

(The ? indicates the sentence is grammatically odd.)

If we are unsure about the number of the collective noun, or to avoid agreement issues, we can add the word members to collective nouns such as committee or use the word players instead of team:

(9) The committee members have submitted their plan.
(10)  Our players hope to win the tournament.