Nouns: Count and non-count

Common nouns are either count or non-count. Count nouns can be ‘counted’, as follows:

one pen, two pens, three pens, four pens...

Non-count nouns, on the other hand, cannot be counted in this way:

*one software, *two softwares, *three softwares, *four softwares...

From a grammatical point of view, this means that count nouns have singular as well as plural forms, whereas non-count nouns have only a singular form.

It also means that non-count nouns do not take a/an before them:

In general, non-count nouns are considered to refer to indivisible wholes. For this reason, they are sometimes called mass nouns.

Some common nouns may be either count or non-count, depending on the kind of reference they have. For example, in I made a cake, cake is a count noun, and the a before it indicates singular number. However, in I like cake, the reference is less specific. It refers to ‘cake in general’, and so cake is non-count in this sentence.