1.Selenium IDE, as a plug-in on Firefox, provides recording function and personal opinions. Don't use this thing if you can write the code by hand.

2.Selenium Remote Control is a client/server system, which can use almost any programming language and test framework to control Web browsers on local or other computers.

3.Selenium Grid can remotely control and run tests on multiple servers at the same time.

4.Selenium WebDriver can drive a browser on a local or remote computer.

Supplement: Java is an object-oriented programming language, which can write cross-platform application software. Java technology has excellent universality, high efficiency, platform portability and security, and is widely used in PCs, data centers, game consoles, scientific supercomputers, mobile phones and the Internet, and has the largest professional community of developers in the world.