Microsoft Visio ( /ˈvɪzi.oʊ/ VIZ-zee-oh), formerly known as Microsoft Office Visio, is a commercial diagramming program for Microsoft Windows that uses vector graphics to create diagrams.

The current version, Microsoft Visio 2010 for Windows, is available in three editions: Standard, Professional and Premium. The Standard and Professional editions both share the same interface, but the latter has additional templates for more advanced diagrams and layouts as well as unique functionality that intends to make it easy for users to connect their diagrams to a number of data sources and display the information graphically. The Premium edition has three additional diagram types with intelligent rules support, validation and subprocess (diagram breakdown) support.

Due to its proprietary file format, few other programs can read Visio files. However, Visio can read and write files as VDX files. VDX is a XML Schema based ("DatadiagramML") and well documented file format. With VDX it is possible to work with an XML based file format without the need to use the old binary file format VSD. VDX is not compressed, hence VSD for the same diagram is usually 3 to 5 times smaller due to LZW-like compression. Visio uses VSD by default. DatadiagramML is supported by many other business process management (BPM) tools like Agilian, ARIS Express, ConceptDraw, Omnigraffle or IBM WebSphere. Omnigraffle Pro on the Mac can read (VSD, VDX) and write (VDX only) Visio files. Starting from version 3.5 LibreOffice can read VSD files in format versions of Visio 2000 and newer.