What is a linear guide?

A simple question but the only answers found are often technically complex. In simple terms, a linear guide is a means to move “something” from position A to position B in a straight line. This “something” can be a sliding door of a cabinet; it can be for a change of position or perspective of a camera; for a glass bottle that is to be filled; for packaging where a label is to be stuck on, as well as for adjustment of the seat of a fitness device. All in a straight line along the shortest possible distance with the help of a linear guide that consists of guide rails or shafts on which one or more linear carriages/bearings are moved. It can be so easy. And if you want to use linear guides without complication, without a long time spent reading manuals and instructions and without having to worry about maintenance, all the better. What linear guides offer such ease of use and convenience: https://www.igus.eu/info/linear-guides-linear-guides