What was diderot's encyclopedia used for?

It helped to spread Enlightenment ideas.

An encyclopedia is a huge set of articles full of information about many, many subjects. The encyclopedia will not give you as much information as a textbook, but it gives a good basic overview of each subject so that you will have a place to start learning. The articles are in alphabetical order, and there is an index so that you can find each one. You can either use an actual encyclopedia in a library or at home, or you can use one of the online encyclopedia systems available.       

Their solution was to tax the colonists.