* Noun: When it refers to the difference between two things, like "There is a stark contrast between the two paintings."
* Verb: When it means to compare two things and highlight their differences, like "The artist contrasted the bright colors with deep shadows."
* Adjective: While not as common, "contrast" can sometimes be used as an adjective meaning "different in appearance or character," like "The contrast in their personalities was obvious."
So, to figure out the part of speech, look at how it's being used in the sentence.