Gravitational wave interferometers all operate on the same physical principle that gravitational waves can be observed by measuring the proper distance between freely-falling objects using beams of light. However LISA will operate in a very different regime to ground-based observatories. LISA’s million-kilometer-scale arm lengths are optimized to observe gravitational waves with milliHertz frequencies. These low-frequency gravitational waves don’t influence detector like LIGO very much since they are optimized to detect frequencies in the tens to hundreds of Hertz. In general, LISA will observe systems with larger masses and increased separations in comparison to those observed by LIGO, Virgo, and KAGRA. LISA sources will also tend to evolve more slowly, allowing longer observations of each source. The two types of observatories complement one another, just like how different types of electromagnetic observatory (e.g. radio, optical, X-ray, etc.) complement one another.