Difference between “selenium server” and “selenium server standalone” jars

Question

Can anyone please explain the difference between \"selenium server\" and \"selenium server standalone\" jars and use of both.

Which one to prefer? When to use which

Answer 1

As per Selenium Documents,

You may, or may not, need the Selenium Server, depending on how you intend to use Selenium-WebDriver. If you will be only using the WebDriver API you do not need the Selenium-Server. If your browser and tests will all run on the same machine, and your tests only use the WebDriver API, then you do not need to run the Selenium-Server; WebDriver will run the browser directly.

There are some reasons though to use the Selenium-Server with Selenium-WebDriver.

1. You are using Selenium-Grid to distribute your tests over multiple machines or virtual machines (VMs).
2. You want to connect to a remote machine that has a particular browser version that is not on your current machine.
3. You are not using the Java bindings (i.e. Python, C#, or Ruby) and would like to use HtmlUnit Driver.

Here is a photo from the old version of selenium website: