The first jointers were long-bodied manually operated planes, which were naturally enough called "jointer planes." Their purpose was to smooth a piece of wood after cutting, ensuring that it was both flat enough and smooth enough for use.
These manual versions of the jointer have long since been replaced by power jointers, which still hold the same basic purpose. However, as power tools, they operate differently than the original. Instead of having one fixed blade, they have multiple blades, placed on a revolving drum. While this cuts much faster than the original manual plane, it isn't as smooth. The ripple appearance that is visible on the surface of many commercially produced boards is a result of being run through a power jointer.
Many woodworkers feel that they don't need a plane today, as boards purchased at the lumberyards have already been smoothed. Of course, if one is cutting their own boards on a sawmill, that would eliminate said reasoning. Nevertheless, a jointer is still a useful tool, providing the ability to thin boards as needed and match their thickness.
More than anything, jointers are used by those who make furniture. When laminating a number of boards together to make a tabletop or the top of a dresser, it's not uncommon to have slight variances in the thicknesses of the boards. This problem increases dramatically when the boards have come from a variety of different sources, as not all sawmills finish their boards exactly the same.
There are a wide variety of jointers on the market today, showing that they are still used extensively, even if a lot of people don't have them in their workshops. While there are not that many manufacturers producing them, each manufacturer has several models to choose from.
Jointers come in a variety of sizes, mostly measured by the width of cut they can produce. The wider ones are also referred to as planers, although the two are essentially the same tool. The major difference is that a true planer doesn't allow material to be edge cut on it, but only cut on the flat. A jointer on the other hand, allows the material to be cut on the flat or edge cut.
A couple of these jointers have helical or spiral knives. This is a relatively recent design innovation, created to reduce the waviness that power jointers typically produce in the sides of boards. While they have many more blades to set up, it is worth it, for the smoother cut that they provide.
The other important feature that some jointers have and others don't is parallelogram ways. This refers to the way that the bed of the jointer meets up with the center part of the jointer's body. By placing the sliding ways at an angle, making the center part of the jointer shaped like a parallelogram, it ensures zero clearance between the blades and the feed table. This reduces chatter, helping to reduce the waviness in the board.
Finally, power and size are important considerations. For the sake of this list, I've tried to stick with planers that were reasonably enough priced that they could be considered for a home workshop. I'll have to say, it was hard picking out the best models to choose. For each one you see here, the same manufacturers make other, larger models. However, those larger models have larger price tags as well. Check out our list of the best jointers in 2022.