Migrating from RC to WebDriver
Information on Updating from Selenium 1 to Selenium 2.
Backing Selenium with WebDriver
The Java and .NET versions of Selenium 2 provided implementations of the original Selenium API
Legacy Firefox Driver
The legacy Firefox Driver was developed as a browser extension by the Selenium Developers. Firefox updated their security model, so it no longer works. You now need to use geckodriver.
Selenium grid 2
Selenium Grid 2 supported WebDriver and Selenium RC. It was replaced by Grid 3 which removed RC code. Grid 3 was completely rewritten for the new Grid 4.
History of Grid Platforms
Information for working with platform names in Grid 2.
Remote WebDriver standalone server
Working with the Standalone Server.
Limitations of scaling up tests in Selenium 2
Summary of additional constraints that arise when running Selenium2 in parallel.
Stealing focus from Firefox in Linux
How to work with Native Events in the Legacy Firefox extension.
Untrusted SSL Certificates
Details on how Selenium 2 accepted untrusted SSL certificates
WebDriver For Mobile Browsers
Describes how Selenium 2 supported Android and iOS before Appium was created
Frequently Asked Questions for Selenium 2
Items of interest for moving from Selenium 1 to Selenium 2
Selenium 2.0 Team
This is who you can blame for the Selenium 2 release.