A distinction that is often useful in philosophy. A token is a single instance, while a type is a set of tokens.
How many words are in the box? Your first answer was probably "two", but you could also answer "one". There are two tokens of the word 'the', but only one type of word.
One application of this distinction is to Occam's razor. When making up scientific theories, it is best to keep the number of types down, but this doesn't apply to tokens.
For example, if you have two equal theories, one of which uses 56 basic particles to construct all matter, and another which uses only 3, the second one is better. But we are talking types here--it really doesn't matter whether you have 1,000,000,000,000,000,000 tokens of the basic particles or 1,000,000,000,000,000,000,000,000. Occam's razor doesn't (seem to) apply to tokens.