Light: Imagine you’re giving a gas-builder, brick, cement, shiffer, a project and saying you need to build a garage. The guests do not understand you, but they see that they are given material, which means that you need to build. Garages they did not see when they were born, but they know how to build toilets. When you need to build, they build a toilet.
The same is true of IE in the form of JS and CSS... >_<