If you don't know the difference between surface web, deep web and dark web, here there are:
- the surface web (the visible one) is made of the sites indexed by the search engines (blogs, e-commerce, forums and all the others).
- the deep web is not crawled by the robots, it contains medical and financial records, the sites for companies, organisations and governments (not meant for public), and so on.
- the dark web is only accesible through some browsers like TOR and is usually linked with the illegal activities.
You can find more information here.