Here's a breakdown:

* Substrate: The molecule that an enzyme acts upon.

* Active Site: The specific region on an enzyme where the substrate binds.

* Inhibitor: A molecule that binds to the active site of an enzyme and prevents the enzyme from catalyzing its reaction.

There are two main types of inhibitors:

* Competitive inhibitors: These inhibitors have a similar shape to the substrate and compete with the substrate for binding to the active site. Since they block the substrate from binding, they prevent the enzyme from functioning.

* Non-competitive inhibitors: These inhibitors bind to a different site on the enzyme (not the active site). This binding changes the enzyme's shape, making the active site less effective or preventing the substrate from binding.

Examples of inhibitors:

* Aspirin: Inhibits the enzyme cyclooxygenase (COX), which is involved in pain and inflammation.

* Penicillin: Inhibits the enzyme transpeptidase, which is essential for bacterial cell wall synthesis.

Important Note: Inhibitors can be naturally occurring or synthetically produced. They are often used in medicine to treat diseases, but they can also be harmful to the environment.