hooks: form when improper contact makes the tooth wear more on one side than another, forming a sharp hook in the enamel. Hooks prevent proper chewing. Long hooks can actually pierce the horse's gum or cheek, leading to infection.
ramps: tooth wears unevenly forming a slant, or ramp. Ramps also interfere with chewing.
steps: caused by overgrowth in a molar table (group of molars) caused by malocclusion (bad contact of chewing surfaces)