Constants in an experiment are values that do not change during or between experiments. They are also known as control variables. Constants are important in scientific experiments because they help increase the validity and accuracy of the experiment or study. By keeping certain variables constant, scientists can isolate the relationship between the independent variable and the dependent variable. Examples of constants in an experiment include temperature, humidity, pressure, experiment duration, sample volume, species, and chemical purity.

Constants are measurable, but they cannot be changed during the experiment or in-between them. Experimental constants can be constituents of natural forces, such as the speed of light or the atomic weight of gold, or properties that are considered constant for the purposes of an experiment, such as the boiling point of water.

In summary, constants are values that remain unchanged during an experiment, and they are important for increasing the validity and accuracy of scientific experiments.