IPods, phones, laptops - the stuff we carry around in our bags is valuable and it can make us a target for thieves.
The police say at this time of year kids are particularly vulnerable because they're starting back at school with lots of new stuff.
In London, a team of officers from Sutton Police have decided to crack down on this type of crime.
Sonali caught up with Inspector Matt Davis to get his top tips on how you can stay safe while you're out and about.
He said children are usually very safe, but there are still things you can do to prevent people taking your stuff, including...
- Keep your mobile phone out of sight
- Don't show off your valuables
- Avoid listening to music while you're walking home so you can be more aware of what's going on around you
- Travel with friends to and from school where possible
- Plan your journey and don't use dark alleys
- Make sure your parents know what time you'll be home