A shared data plan provides a set amount of data for all smartphone users on the plan. As individuals use data, the total amount of data for the month goes down.
Families with multiple cell phones on one plan may benefit from shared data. Instead of buying individual data plans, everyone shares the same pool of data. If some members only use a little data and others use more, the total used for the month balances out. Data use from any user on the plan beyond the monthly allotted amount results in additional fees. Families with heavy data users may need to increase the monthly shared data amount.