Screen printing is an old printing method in which a stencil is used to transfer ink on a flat substrate, but in places designed specifically to prevent the ink from spreading. This kind of printing usually has very poor print quality and can often result in poor art. It was once popular for use on hats and other articles of clothing as a way to create a decorative border or background, but in practice this kind of printer has fallen out of favour. However, in some cases it can still be used successfully and is particularly useful when creating screen printed garments. My link
Screen printing can be either digital or analog, using either solid inks or semi-solid inks. Both types of printers require separate inks to perform, and typically a solid color printer will produce more detailed, brighter images than a semi-solid ink. The solid inks tend to be cheaper, but they have lower print quality. Semi-solid inks tend to have higher print quality and are less expensive than the solid inks. Usually a manufacturer will choose particular inks that can best meet their printing needs, although sometimes a combination of both is available.
Pre-press methods are also used in screen printing. A screen printing service will generally offer a range of pre-press tools including stencils, pre-loaded images and rollers. These tools are great if you need a high quality result quickly without having to wait for the machine to dry – but in many cases they are unsuitable for screen printing, with poor print quality and tiny gaps between stencil outlines. Instead, a high quality pre-press solution would be required if you wanted to create screen printed garments or other high quality artwork.