The commonly-used Galaxy Classification indicates a Galaxy's morphology, i.e., shape. Edwin Hubble developed the basic classification still used, the Hubble Types, known collectively as the Hubble Sequence:

• Elliptical Galaxy: E0 through E7.
• Spiral Galaxy or Disk Galaxy - SA or SB (for Barred) followed by a,b,c,d re how tight are the arms.
• Lenticular - bright central Bulge in disk but no visible spiral.
• Irregular (or later described as Amorphous).

More recent developments, generally indicated by a suffix or prefix, add more detail, often distinguishing galaxies formerly classified as "irregular". For example, the classification "SBm" is based upon the Large Magellanic Cloud's form, which does have characteristics associated with the classic barred spiral. In the less-developed system, the LMC falls under "irregular".