Many apps and games have a PEGI label (Pan-European Game Information). This label guarantees that games are in keeping with your children's age. Downloads in the App Store and Play Store have a PEGI code. The recommended minimum age can be viewed for every game. Read the explanation about the different PEGI labels on pegi.info.

Downloads can be restricted based on the PEGI label:

 In the Play Store, go to Menu > Settings > Parental controls.

 To set this for the App Store, go to Settings > General > Limitations > Allowed Content on your iPhone or iPad.