Versions of Selenium

The different versions of Selenium are as follows-

Selenium 1(Selenium RC) Selenium 2 (Selenium Web-Driver) Selenium 3  
The first version of Selenium is Selenium 1, which includes Selenium IDE, Selenium RC, and Selenium Grid.  The second version is Selenium 2, which includes Selenium IDE, Selenium Web -Driver 2.x, Selenium RC, and Selenium Grid.  The Third version is Selenium 3, which includes Selenium IDESelenium Web-Driver 3.x, and Selenium Grid.  
These are the first and oldest versions of Selenium.Selenium 3 is the Latest version of Selenium.  
Selenium -1 introduced in 2006.Selenium-2 introduced into the market in 2011.  Selenium-3 got released in 2016.  
In selenium 3, the support of Selenium-RC is removed.  

These are the main core languages which are most commonly used in projects-

LanguagesClient Version
Java    3.141.59
C#       3.14.0

Latest Release of Selenium Components:

Selenium ComponentsDescriptionLatest Version
Selenium Standalone Server The Selenium stand-alone Server is needed to run remote Selenium Web-Driver. Directly Selenium 3.X is no longer capable of running Selenium RC.Latest version 3.141.59
The Internet Explorer Driver Server The internet explorer driver required a server if you want to make use of the latest features of the Web-Driver Internet Explorer-Driver. Latest version 3.14.0    
Selenium Client & Web-Driver Selenium client & web-driver interact with the Selenium Server (Selenium RC, Selenium Remote Web Driver) or create local Selenium Web Driver scripts.These languages include both 1.x and 2.x style clients. Latest Version of Web-Driver-3.141.0  
Selenium-IDE  It is a Firefox and chrome plug-in which records and plays back the user interactions with the browser.Latest version 2.9.1