What is the difference between SDK and SDK base 2006, 2007, 2013 and other?

[W+M1 GAMING ♕]

I am using hammer engine for cs and now I wanted to use source sdk. Which version should I use?

[Lychy]

For counter-strike, you need to head to your counter-strike source folder and find hammer.exe in the bin folder. You only need Source sdk 2013 for mods, the rest are for backwards compatability

[Wazanator]

To build off of what Lychy said.

2006/2007 (the ones you find in the "Source SDK") are much older branches that Valve and really no one else supports anymore. You only run into instances of people using it who don't want to follow the basic setup tutorials and just use the included mod wizard instead which eventually results in them needing to migrate to 2013 because no one wants to help someone using old code.

In 2013 the Steampipe update happened and Source SDK 2013 was released. All older Valve Source games were migrated to the 2013 branch to align themselves so patching would be easier and they could support Windows, MacOS, and Linux among other things.

The only reason someone who is making a mod not use 2013 are:

• You are using leaked code which would be illegal and you could never release on Steam
  
• You are given a full engine license so you can use a more modern branch of the Source Engine like Portal 2's or CSGO's
  
• You are wanting to use Source Engine CE which runs on the Alien Swarm branch which is much closer to L4D's branch BUT has no support now so it has potentially security issues among other things like no Linux/MacOS support.

If you are wanting to make a single player Source Engine mod I would recommend following one of the many tutorials online (either mine or the one of the wiki) and once you understand the basics of mod setup use MapBase which is a well polished community branch that is running on Source SDK 2013.

https://developer.valvesoftware.com/wiki/Source_SDK_2013

https://wazanator.com/tutorials/sp2013setup/

https://www.moddb.com/mods/mapbase