Share your experience!
Mobile data = internet access through your network/carrier (NOT wifi), it should be enabled or disabled at your discretion, if you have unlimited data you don't have to disable it, if you want to save battery you should disable it if you are not using it.
It's fine to have it disabled all the time
Mobile data?
So your at home using the wifi but you go out and need to use the internet so you turn on mobile data and you can now use the internet - So you could whilst out and about check your emails - Visit this forum and check replies to your questions,
But bear in mind that when you take out a contract you may have restrictions like a 2GB limit and after this 2GB limit is reached you may be charged extra where as using your wifi there will be no charge except for what you pay your broadband provider