The term refers to a method of pushing paint through a screen made of a fine mesh, prepared so that some of the mesh doesn't let paint through, to create a design. It is also known as silkscreen, silk-screening and serigraph referring to the original material that printing screens were made of and the ability to create a series of prints.
Substrate it the surface that is being printed. Substrates are varied, with the most common ones being fabric and paper. Screen printers will refer to their screens as having a substrate and a squeegee side, respectively the side where the screen touches the substrate and the side where the ink is pushed through with a squeegee.
A squeegee is similar to a wiper, used to squeeze ink through the mesh of the treated screen onto the substrate. Squeegee blades can be hard or soft and can have square, rounded or pointed blade edges for the use on different substrates.
Durometer is the number indicating the hardness of the squeegee blade, the higher the number the harder it is with 70 being the most common durometer. Soft round squeegees are more often used for fabrics while hard sharp edged and square squeegees do well on non-porous surfaces.
Screen Mesh Prints:
The screen mesh is the polyester used in screen printing for the screen. It comes in a thread count of 40 to 400. The higher the thread count, the less ink it will let through.
Screen mesh comes in either white or yellow. When exposing a positive onto mesh the color can make the difference between soft and sharp images. White mesh reflects the light of the exposure to all sides and so creates softer lines while the colored mesh with less reflection produces a sharper image.
Screen Printing Frame:
Last, but definitely not least, is the screen printing frame which holds the screen mesh. They're made from wood or aluminum. Wooden frames don't last anywhere near as long as aluminum frames which cost a great deal more. Frames are often pre-tensioned but re-tensionable frames with rolling bars that can tightened the mesh up to the tension required are also available.