In most modern homes, you will only find grounded outlets. They are important for proper functionality of many appliances, for the safe use of surge protectors and just safety in general. In older homes, however, there is the possibility that you have very few, or even no grounded outlets available. Even if you have what looks like grounded outlets, without opening them up, you can’t really tell if they are properly grounded or not. It is possible that a previous homeowner installed grounded receptacles without a ground connection just to be able to use them with grounded appliances.
In your bathroom and kitchen you will usually have GFCI outlets installed, which will protect you from electrocution, and there is nothing that says that you cannot install them in other places. If you do decide on rewiring your home to get grounded outlets everywhere, you should consult a professional electrician to make sure that the job is done properly.