How can you maximize or minimize friction?

Friction can be maximized or minimized in several ways depending on the material, device construction and purpose, for example:

Minimizing friction of a circling axis can be made by bearings, which usually have rolling balls. Rolling has usually less friction than sliding.

In slide systems, friction can be minimized in various ways such as:

1. Polishing the surface of both sliding sides (the opposite will increase friction)
2. Adding a liquid such as oil between them. Oil fills the micro gaps on the surfaces therefore creating a slippery surface
3. Using certain techniques, e.g. air insulation, magnetic insulation