Interferometry is a technique used in physics and astronomy to measure the properties of waves, such as light or sound, by analyzing the interference patterns that occur when two or more waves interact with each other. In astronomy, interferometry is commonly used to combine the signals from multiple telescopes to create a larger, more powerful telescope. This allows astronomers to achieve higher resolution and sensitivity than would be possible with a single telescope. Interferometry is also used in other fields, such as optical testing, telecommunications, and measurement of small distances.