Is a client/server system that allows you to control web browsers using programming language and testing framework.
Selenium automates browsers. That's it. What you do with that power is entirely up to you. Primarily it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well.
Selenium is a suite of tools to automate web browsers across many platforms. Selenium runs in many browsers and operating systems and can be controlled by many programming languages and testing frameworks.
The best learning quote
Tell me and I forget, teach me and I may remember, involve me and I learn.
- Benjamin Franklin