The Xfce4-screenshooter is an application that can be used to take snapshots of your desktop screen.
Gnome Screenshot
GNOME Screenshot is a small utility that takes a screenshot of the whole
desktop; the currently focused window; or an area of the screen.
KSnip
Ksnip is a Qt based cross-platform screenshot tool that provides many annotation features for your screenshots.
Flameshot
Powerful yet simple to use screenshot software.