A collage (From the French: coller, to glue) is a work of formal art, primarily in the visual arts, made from an assemblage of different forms, thus creating a new whole. Use of this technique made its dramatic appearance among oil paintings in the early 20th century as an art form of groundbreaking novelty.
An artistic collage work may include newspaper clippings, ribbons, bits of colored or hand-made papers, portions of other artwork, photographs, and such, glued to a piece of paper or canvas.

Techniques of collage were first used at the time of the invention of paper in China around 200 BC. The use of collage, however, remained very limited until the 10th century in Japan, when calligraphers began to apply glued paper, using texts on surfaces, when writing their poems.

The technique of collage appeared in medieval Europe during the 13th century. Gold leaf panels started to be applied in Gothic cathedrals around the 15th and 16th centuries. Gemstones and other precious metals were applied to religious images, icons, and also, to coats of arms.

In the 19th century, collage methods also were used among hobbyists for memorabilia (i.e. applied to photo albums) and books (i.e. Hans Christian Andersen, Carl Spitzweg).
The term collage derives from the French "coller" meaning "glue".
This term was coined by both Georges Braque and Pablo Picasso in the beginning of the 20th century when collage became a distinctive part of modern art.

Creating a collage out of photographs
What is a collage?

Collage is a graphic work made using a set of different images – photos and drawings.  Collage is a technique of creating a whole new image out of other images’ parts, usually using special software as Adobe Photoshop. Working with layers is the essence of collage creation. Different types of overlay, bending and transparency can be used.
In this lesson we will look at how a collage can be created using mask tool.
1) Go to www.google.com, choose search Images and type in the name of the image to search for. In our case it’s Computer Games.
2) Specify the size of the image to look for - Extra Large Images.
3) Click “Search Images” or press Enter.
4) Choose the image you like and save it in your folder.

To specify the size of the image use Image/Image Size command. In the window that pops up type in the size of the image; Resolution - 72, size - 22.222 inch. х16.667inch.

For our collage the image needs to be scaled down a little. To do this: 1) Uncheck “Resample Image” option. 2) Set resolution at 150. The size of the image will change automatically. Pay attention: the higher the resolution, the smaller the image becomes, and vice versa. 3) Save changes by clicking ОК.

Drag the scaled down image to a new document.

After blurring the image edges you will need to blur the image itself in such a way that one would see another image (underlying image) through it. To do this keep changing Opacity value by 10% and trying the brush on the edge of the image until the desired result is achieved.

Now save the document using “File/Save As” command from the main menu.

Now save the document using “File/Save As” command from the main menu.