As a woodworker, you won’t be able to escape the essential skill of forming flat boards. For our large tabletop we’ll need to join several boards together. There are several techniques at your disposal. The choice of your project will often depend more on your available equipment and time than issues of strength and design.
The simplest option is a “rub joint”. This simple joint is formed by jointing the surfaces so they are flat and smooth and gluing the long grain together. Simple.
This joint is not often used as it has a problem. With seasonal variation and the natural movement of the wood the wood can warp and the boards can move reletive to each other. Not a good look.
This movement can be prevented by using a "mechanical joint." This is where in addition to glue the boards are physically limited by a piece of wood which crosses the joint.
Dowels or loose tennons are a simple option. Simple to install with a dowel jig and drill.
Biscuit joints are one of the most popular options. With the use of a biscuit joiner they are faster to install then dowel and provide good alignment and strength.
Spline joinery is also simple and effective. A groove is cut in each piece on a table saw, router, or biscuit joiner. An additional piece is cut to match and glue in place. Splines with grain perpendicular to the boards provide addition shear strength.
A sliding dovetail joint is an attractive alternative to the spline. It is more difficult to cut but provides mechanical stength vertically and horizontally.
Tongue and groove joinery doesn't require additional wood but it does come at the cost of width of the origional boards.