This putty-like sticky substance comes in a package, usually in small bricks. Several brands exist, including Blu-Tack, Elmer's, Scotch and Duck Poster Putty. Pull off a small piece of the putty from the brick, roll it in the palm of your hand, and then squash it flat. Stick a bit of it on the back of your photos to hang them up. It's important to remember that the blue putty can stain your walls if you leave it up too long. Prevent this issue by using white putty or rotating the putty behind your pictures.
Architect's tape allows you to tape up your photos without damaging the walls or ripping the photos. The adhesive on architect's tape is rather weak so it won't tear paper, which means you can also put it on the front of your pictures without ruining them. Find architect's tape at arts and crafts stores. The main drawback to using this product is that it doesn't have a strong adhesive, so your photos may fall down.
Adhesive clips offer you a peel-and-stick option for hanging your photographs on the wall. These clips are usually made of plastic or metal and come with an adhesive strip on the back. Peel off the plastic strip that covers the adhesive, and then stick it on your wall. It comes with a clip in the front so you can stick your photos into the clip. The adhesive tends to be quite strong, so be careful not to pull the paint from the wall when you remove them. You can also find magnetic versions, which allow you to stick your photos on metal walls.
While using some kind of adhesive provides you with a quick solution to putting up pictures, putting them in frames and hanging them up may offer you a better solution in the long run. Doing this protects your photos from getting torn by the adhesive and shields them from some of the damage that air and dust can cause. The nails you use to hang up the frames will leave holes in the wall, but you can easily spackle and paint over these when the time comes.