Salicylic acid (2-hydoxybenzoic acid) is a white solid which can be extracted from plants such as
the willow
or
meadowsweet
Aspirin is an ester of acetic acid with the alcohol function of salicylic acid:
Aspirin is prepared by esterification of salicylic acid with acetic acid:
or, with a better yield by esterification of salicylic acid with acetic anhydride:
Adapted from → Kie_gb