Here's why:

* Derived from: Antibiotics are primarily derived from microorganisms themselves, often bacteria and fungi. They produce these substances naturally to compete with other microbes.

* Used to destroy microorganisms: Antibiotics work by targeting specific processes essential for the survival of bacteria, such as cell wall synthesis or protein production. This disruption leads to the death or inhibition of the bacterial cells.

Important Note: Antibiotics are not effective against viruses, which have different structures and replication mechanisms.