ODS is the spreadsheet format for spreadsheet software that follow the Open Office Document Format. .ODS is the default spreadsheet format for the OpenOffice.org Calc.

These can be opened with any OpenOffice-compatible program, including NeoOffice (Mac), AbiWord (Mac & Windows), and KWord (Unix) and can also be imported into Google Docs. ODS files are based on the OpenDocument format (ODF), which became the native format for electronic office documents such as spreadsheets, charts, presentations and word processing documents replacing the OpenOffice.org XML format, for open standards based applications.

Related: What is a ODT file?