A Petri dish is a shallow, flat, cylindrical, lidded container made of clear glass or transparent plastic. It is commonly used in laboratories for culturing and observing microorganisms, such as bacteria, fungi, and algae.

The Petri dish is named after its inventor, Julius Richard Petri, a German bacteriologist. He developed the dish in the late 19th century as a more convenient way to culture and observe microorganisms.

Petri dishes are typically made of glass or clear plastic, such as polystyrene or polycarbonate. Glass Petri dishes are reusable but fragile, while plastic ones are disposable and more convenient for sterile work.

The primary purpose of a Petri dish is to culture microorganisms. They provide a controlled environment for the growth of bacteria, fungi, and other microorganisms, making it easier for scientists to study and observe them.

Petri dishes can be sterilized using several methods, including autoclaving, dry heat sterilization, or exposure to ultraviolet (UV) light. Sterilization is essential to prevent contamination during microbiological experiments.