A digital camera is a camera that takes video or still photographs, or both, digitally  by recording images on a light-sensitive sensor.

Many compact digital still cameras can record sound  and moving video as well as still photographs. In the Western market, digital cameras outsell their 35 mm film counterparts.

Digital cameras can include features that are not found in film cameras, such as displaying an image on the camera's screen immediately after it is recorded, the capacity to take thousands of images on a single small memory device, the ability to record video with sound, the ability to edit images, and deletion of images allowing re-use of the storage they occupied. Digital cameras are incorporated into many devices ranging from PDAs and mobile phones (called camera phones) to vehicles. The Hubble Space Telescope and other astronomical devices are essentially specialised digital cameras.

Type of camera
Video cameras :- Used to record moving images

Still camera :- used to take  still photos 
Compact camera :- small and portable camera provides many features

Bridge cameras :-Bridge or SLR-like cameras are higher-end live-preview cameras that physically resemble DSLRs and share with them some advanced features, but share with compacts the live-preview design and small sensor sizes.

Digital single lens reflex cameras :-Digital single-lens reflex cameras (DSLRs) are digital cameras based on film single-lens reflex cameras (SLRs), both types are characterized by the existence of a mirror and reflex system

Digital rangefinders :-A rangefinder is a user-operated optical mechanism to measure subject distance once widely used on film cameras. Most digital cameras measure subject distance automatically using acoustic or electronic techniques, but it is not customary to say that they have a rangefinder.

Professional modular digital camera systems :-This category includes very high end professional equipment that can be assembled from modular components (winders, grips, lenses, etc.) to suit particular purposes. Common makes include Hasselblad and Mamiya. They were developed for medium or large format film sizes, as these captured greater detail and could be enlarged more than 35 mm.

Line-scan camera systems :-A line-scan camera is a camera device containing a line-scan image sensor chip, and a focusing mechanism. These cameras are almost solely used in industrial settings to capture an image of a constant stream of moving material.