Getting rid of corruption [duplicate]

I may be completely wrong but:
You can contain it by ensuring there is space between the corruption and your normal world (area you don't want to be corrupt). For late-game, you'll have to have a border of at least 2/3 layers of non-corruptible materials, such as clay.

To clear it out - Simply remove all Ebonystone and purify everything.

Note: A 'border' means several spaces of air, followed by the clay border.

Sunflowers stop the spread of corruption.

You can use Purification Powder to push the corruption back, but if you want to keep it back, you could simply use sunflowers. The same goes for the Crimson.