Selective Serotonin Reuptake Inhibitors (SSRIs) are a type of antidepressant drug.
Normally, the neurotransmitter serotonin is released by a nerve cell, then re-absorbed back into the same cell. The re-absorption is called "reuptake." SSRIs slow down reuptake, which makes the serotonin available to your brain for a longer period of time.
Examples of SSRIs are: