Who can I claim on my return?
You can claim many relatives that financially rely on you for support as "dependents" on your tax return, though the rules for different relatives can be a little complicated.
The most common dependent is your children. Generally speaking, the IRS allows you to claim your child if they live with you most of the year, they are not financially independent, they were under 19 on the last day of the year, and you are the family member best positioned to claim them. You can also treat your stepchildren and nephews/nieces as your children under this definition.
You can in some cases claim other relatives, including aging parents, if you provide for most of their needs financially, and they earn very little themselves.
Various exceptions apply to both of these definitions. Most tax preparation services (including GetYourRefund) will walk you through the definitions and make sure it is appropriate for you to claim your relatives.