The barbell is a two-handed weight lifting equipment made of two weights attached to a bar, lengthing between 1.2 and 2.2 m. Some models use specific shapes, such as the EZ bar with its curved profile, or triceps bars with its parallel handles. The smaller version, designed for single-hand use, is called the dumbbell.
Barbells are usually designed to load or unload weights easily by adding or removing circular plates on each side of the bar.
Compared to dumbbells, they allow to lift a lot more weight, thanks to the stability they provide. The range of exercises is however more limited and specific.
I'm using Powerblocks with the straight bar addon, which turns them into a regular barbell.