There exists a wide variety of filaments, which all come with different properties, but the most important one is the diameter.
So if you want to buy some printing material its important so look out for the right size.
The Ultimaker 3 printer in the LAB uses 2.75mm Filament diameter.
Warning from personal experience: Don´t buy filament marketed as 3 mm because that is too thick for the Ultimaker and will get stuck.
Also sometimes the tolerances on the diameter is not so tight when buying cheap filament, this will lead to lower quality prints.
That is because the amount of material that the printer will extrude will relate to the diameter of the filament and if that changes every few meters the structure in your print will also be not uniform.
This can be considered as kind of standard 3d printing material. It is a plastic with a organic source which is easy to print.