New wall-covering can transform a room, going from boring to beautiful. If you just bought a pre-loved home that has the original wallpaper from 1950 plus years of wallpapering over the original wallpaper, you are going to want to do some redecorating.
You are talking major work if you have to remove more than one layer of wallpaper or wallpaper that has been painted over. If the wallpaper was not applied to a properly sealed surface, removing it without damaging the wall can be nearly impossible.
For this type of redecorating project you will find the job is much easier if you rent a wallpaper steamer. In most places it costs about $15-20 for a half-day. Or you may want to buy a DIY model, about $50-100, if you have a lot of wallpaper to remove. (Pro models cost about $500.)

A Wallpaper steamer is a hotplate attached to a hose extending from a hot water reservoir. A heating element in the reservoir heats the water and directs steam to the hotplate.
Although you can use a steamer with relative confidence on plaster walls, use caution on drywall, which is much more vulnerable to moisture.
Remember that steam is boiling hot. It can burn you.
Wear latex or rubber gloves to protect your hands.
Wear long sleeves. Consider wearing a Tyvek suite. Steam can't penetrate straight to the skin.
Make sure you are using a step stool if you are working above chest height.
Before using a wallpaper steamer you will want to read the operators manual and safety guide so as not to sustain any injuries and to make sure you use the device properly. The following steps are typical of most machines.

Again always use caution when using the wallpaper steamer. Do not allow small children to be around this piece of equipment.
Make sure that you have a drop cloth covering the area of the floor you are working on. When the wallpaper comes off the adhesive will make a mess of a carpet and can mar the finish on hardwood floors as well.
When you have to remove wallpaper using the wallpaper steamer may not be the easiest way to go on the project, but it some cases it will be the most effective method. Often that's something you can't know until you start the job of removing wallpaper.