Eggshell - Traditionally refers to an oil-based paint with a silky finish, suitable for interior walls and woodwork. Water-based alternatives are now available.
If you decide to do your own body work discuss it with the paint shop first. They'll probably have recommendations on the type of primer you use. Some brands will be more compatible with their primers or color coats. The rule of thumb is to stay within the same brand of paint, both for prep and color. Even the cheapest paint shops typically use a brand name on their intermediate and higher paint jobs. Find out what it is and use the same brand as your primer coat. This will ensure you don't create adhesion problems for yourself down the road.
There is still no standard labelling scheme for paint. The blue globe label, pioneered by B&Q, led to VOC reduction on the mass market and has been adopted by other brands, while the European Ecolabel, recognised in 15 EU member states, looks like a flower and appears on brands such as Earthborn. Germany also has a Blue Angel label and there is a green Nordic Swan as well. You will find more detailed information on most of the paint company's websites, as well as a wealth of practical and design advice.
Gloss - These paints have a high sheen level and are usually used on woodwork.
If you have large holes or cracks in a wall purchase a small can of vinyl repair paste. The reason I prefer it over regular wall Spackle is that after it dries it is much harder and sands easily. You can even use it for minor wood repair in a pinch.
Satin paints offer a good combination of easy-clean and moderate sheen. These paints go a step above eggshell in scrubbing ability. They perform and look great in just about any room.
There are different types of paints that is either water-based or solvent-based that produces different finishes that is measured by its sheen factor. "Sheen" is a term used to describe the degree of light reflection the paint has. Lesser sheen for an interior or exterior paint means it has lesser stain resistance.