IS may refer to:

• Is, the third-person singular present tense of the English language verb “to be”, frequently used as a copula

• Immune system, organic mechanisms that protect against disease
• Immunosuppression

• .is, the Internet country-code top-level domain for Iceland
• Information science, the study of data collection, manipulation, and dissemination
• Information systems, organizations of data-processing persons, records, and activities
• InstallShield, a software tool for creating software installers for Microsoft Windows

• Image stabilization, a family of techniques to reduce blur caused by lens shakes