Ionian - Major scale
Dorian - Minor scale with raised 6th
Phrygian - Minor scale with flat 2nd
Lydian - Major scale with sharp 4th
Mixolydian - Major scale with flat 7th
Aeolian - Minor/Relative minor scale
Locrian - Minor scale with flat 2nd and 5th
Most of the time, the modes just change one note from the scale it came from, but they can sound pretty exotic