When we use the indefinite article an before other, we write it as one word: another. Another means ‘one more’ or ‘an additional or extra’, or ‘an alternative or different’.

• When other is a determiner, it does not have a plural form:

These boxes are for books. The other boxes are for clothes.

Not: The others boxes …

• When other as a pronoun refers to more than one person or thing, it takes the plural form, others:

Some scientists think we should reduce the number of flights to prevent global warming; others disagree.

Not: … other disagree.

• Other must have a determiner before it when it comes in front of a singular countable noun. If the noun is indefinite (e.g. a book, a woman, an idea), we use another:

I’ve posted the first package. What shall I do with that other package?

Not: What shall I do with other package?

After a month in Bolivia, I was ready to move to another country.

Not: … to move to other country.

• We write another as one word:

There is another car park a little further down the same street.

Not: There is an other car park …

• Another is singular. We don’t use it with plural nouns:

Other interesting places to visit include the old harbour and the castle.

Not: Another interesting places to visit …