Internet data works similarly to your phone data plans in that you receive a certain allotment of gigabytes (GB) to "spend" over the course of a month based on your online activity. Most cable internet companies implement data caps starting at 250GB. For some context, 1GB is needed for about one hour of Netflix SD streaming and 3GB per hour for HD streaming. If you're just using the internet for light emailing and web browsing, you can stay near 50GB per month. Heavy users should look for a plan with around 500GB of data or more. If you happen to go over your data limit, providers will issue a warning and eventually charge a fee for more data.