one way to find the type of edition is looking on the title bar of the browser window. Is there any other way to find it out? though it is very basic question, but i need to know it.
Click on Your Name -> Setup -> Administration Setup.
Top of the loaded page you can see which edition you are using. .
WSDL checking option to identifying the Salesforce edition based on @KeithC's comment. Checking at the Administration Setup is the best option to identify the edition.
2FYI, I don't see the edition name in the Enterprise WSDL. (In the header comment there is information about the packages referenced including namespace and version.)– Keith CApr 2, 2014 at 9:13
Agreed @KeithC. I think it's a misunderstanding the Enterprise Web Services API Version xx.x statement. I'll edit my answer– highfiveApr 2, 2014 at 9:19
Once you have successfully logged onto SFDC ORG, the browser window/tab title (Salesforce.com - will provide you with the edition like Developer, Enterprise, Unlimited, etc. you have logged in.
For Firefox (refer below)
For IE (refer below)
Go to quick search, type and navigate to Company Information.
Look for Organization Edition
Here you will find the edition you are using.