DSLRs or Digital SLR cameras (SLR means "single lens reflex") are the modern replacements for the 35mm cameras used by professional photographers for decades.  Many systems even continued using 35mm lens mounts so that photographers could "bring their old lenses along" when they made the switch to digital.

 

Top-of-the-line DSLRs have the highest resolution of any digital camera systems.  It's not unusual for the latest models to have the ability to record images in 12 or more "megapixels".  And the size of the camera sensors now often match the size of the old 35mm film frame, removing the need to remember the "magnification factor" that comes with smaller sensors.

 

Ignore the silly arguments about whether the better SLRs are made by Canon or Nikon or Fujifilm or ...   You'll have to look at the results at an unrealistic level to see any difference caused by the actual camera manufacturer - at these price levels everybody's making very good equipment.  Far more important is the quality of the lens - and the creativity you put into your photo-making.  (Be careful when considering camera plus lens "kits" - those often include lower-quality lenses.  You'll probably be better off buying the camera body separately then choosing lenses that work best for the type of photography you want to do.)