What is a "data plan"?
As mentioned in the excerpt, quoted from about.com:
A data plan is part of the service that mobile operators offer to give you connectivity anywhere under the sky.
This might be a real flatrate, or a "fake one": in many cases, a real one would be quite expensive. So you might decide for a given limit of "full speed", after which the speed is reduced to a minimum (still sufficient to check for mail -- but hardly usable to stream videos). Depending on how much you need, and how much you want to spend, the included amount of "full-speed traffic" might vary.
Though the topic "data plan" as such would be an "Android independent phone question" (and as such off topic according to our FAQ), there are still topics not falling into this category. Check existing questions to figure out which this might be, by simply clicking on the tag name.
- data-connection: for issues with your mobile data connection
- data-traffic: amount of data transferred. Use this for questions/issues like finding out which app is eating up your data plan.
- wi-fi: using your home WiFi network
- bluetooth: another wireless technology, but limited to short distances.
- usb: this can also be used to transfer data, but is not wireless.
- mobile-data: transferring data via your mobile data connection (2g/3g/4g)
- background-data: Data transferred in the background, i.e. without explicitly being triggered. This usually includes things like synchronizing your calendar and contact data.