'Another' is simply the words 'an' and 'other' written as one word. The answer isn't quite as simple as a distinction between singular and plural, however. Basically, you use 'another' in any situation when you would use 'a' or 'an' before the noun. You use the indefinite article 'a' or 'an' for singular countable indefinite nouns, and you use the word 'another' in exactly the same way. Singular countable indefinite ----> a book ------> ANOTHER BOOK Singular uncountable indefinite ---> information ------> other information Plural countable indefinite: ------> books ---------> other books Singular countable definite -----> the book -------> other book Singular uncountable definite ----> the information -----> other information Plural countable definite ----> the books --------> the other books As you can see, 'other' is an adjective which you can put before any noun. If there is a determiner (a, an, the, this, those, that, these, my, your, his etc) before the noun, the word 'other' goes between the determiner and the noun e.g.: my other book, this other book, those other books, that other information But, instead of saying ' a other book' or 'an other book', we write the two words 'an' and 'other' as one word ---> 'another book'. It really is that simple.

Another is SINGULAR - I want another piece of bread. OTHER is PLURAL - There were many other people at the meeting. http://www.englishcurrent.com/grammar/other-another-difference/