We have group specific inhibitors. We have substrate analogs, also known as affinity labels, and we have suicide inhibitors, also known as mechanism based inhibitors. Now, we can actually use these three different types of Irreversible inhibitors to actually probe and study the residues found inside active sites of enzymes. And out of these three different types of groups, the most specific type of group is the suicide inhibitor. And the least specific type of group is the group specific inhibitor. So let's begin by discussing the group specific inhibitor.