A laboratory (informally, lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed.

Laboratories used for scientific research take many forms because of the differing requirements of specialists in the various fields of science and engineering. For example, a physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras to observe behavior. In some laboratories, such as those commonly used by computer scientists, computers (sometimes supercomputers) are used for either simulations or data analysis. Scientists in other fields will still use other types of laboratories. For example, engineers use laboratories as well to design, build and test technological devices.