OOCSS stands for object-oriented CSS. This approach has two main ideas:

• Separation of structure and design
• Separation of container and content

Using this structure, the developer obtains general classes that can be used in different places.

At this step, there are two pieces of news (as usual, good and bad):

• Good: reducing the amount of code by reusing it (DRY principle).
• Bad: complex support. When you change the style of a particular element, you will most likely have to change not only CSS (because most classes are common), but also add classes to the markup.

Also, the OOCSS approach itself does not offer specific rules, but abstract recommendations, so how this method ends up in production varies.

As it happens, the ideas in OOCSS inspired others to create their own, more concrete, ways of code structuring.