Putting stuff up on the wall can require some extra support, especially since most homes only have drywalls. Drywall is an excellent building material, but it is not very good for mounting stuff. This is why wall anchors are useful for homeowners.
There are many different designs to wall anchors, but the basic idea is that the anchor lets you attach things to the wall that otherwise would rip right out of it. They come in a wide range of weight ratings, and it is important that you pay attention to it or you could end up with things falling off the wall, taking a large chunk with it.
You should also be aware that the integrity of the wall makes a big difference in what the wall can handle. If it has been damaged for some reason, it might not be sound enough to hold up the weight, even with an anchor.
For the heaviest objects, wall anchors might not be enough, but you would be better off trying to find a stud to mount them on.