SIT may refer to:

• Sit (island), an island in Croatia
• Sit, Bashagard, a village in Hormozgan Province, Iran
• Sit, Gafr and Parmon, a village in Hormozgan Province, Iran
• Sit, Minab, a village in Hormozgan Province, * Sit-e Bandkharas, a village in Hormozgan Province, Iran
• Sit River, a river in Russia
• Sit-e Bandkharas, a village in Hormozgan Province, Iran

Sitting is a rest position supported in humans by the buttocks or thighs where the torso is more or less upright. Sitting for much of the day may pose significant health risks, and people who sit regularly for prolonged periods have higher mortality rates than those who do not.

StuffIt is a family of computer software utilities for archiving and compressing files. Originally produced for the Macintosh, versions for Microsoft Windows, Linux (x86), and Sun Solaris were later created. The proprietary compression format used by the StuffIt utilities is also termed StuffIt.