Lotus 3 Worksheet (.wk3)
The WK3 file extension stands for Lotus 3 Worksheet, a spreadsheet file format developed by IBM for its Lotus 1-2-3 software. Introduced in the 1980s, WK3 files store data in cells organized into rows and columns, similar to modern spreadsheet formats. Although Lotus 1-2-3 is now discontinued, WK3 files can still be opened with software like Microsoft Excel (versions prior to 2007). This format played a significant role in the early days of personal computing and data management.