Acetone is a pure solvent with an endless variety of applications. It is a very aggressive solvent, dries extremely quickly, and is zero residue. Also, it is exempt from VOC regulations in most jurisdictions. It is highly flammable, so appropriate precautions are required before use.
Acetone has many uses specific to electronics. It may be used as a cleaner or stripper. It aggressively dissolves heavy greases and stubborn residues, quickly stripping coatings, and even eventually destroying most encapsulating and potting compounds. It may be used as a thinner for fast dry coatings, or as a multi-purpose solvent, and in 3D printing it is useful for smoothing ABS.
NOTE: This can only be shipped by ground!!