What are the most common Linux equivalents of MS-Paint? And what file formats do they prefer?

For example, if you tell MS-Paint to save a file, it will show the .bmp or .png filetype (depending on the version of Windows), which you can choose by default, or choose a different filetype. What filetypes would the Linux equivalents of MS-Paint choose by default? And what other filetypes do they allow you to choose? Do they have .png and .bmp?