What is the difference between DSLR, SLR and Digital Camera?

Can I develop pictures with any of them? Sorry, probably a stupid question, but I'm lost!

You have good answers already, but I've got this one on the clipboard already, so you aer lucky winner number two tonight.

SLR's can be either DSLR's (digital) or film SLR's. People often just say "SLR" when they are meaning film SLR's. DSLR's are digital cameras, but most of the time when people use the term - especially if it is referring to "something else" besides a DSLR, they mean a "regular" digital camera, also known as a point & shoot, also known as a P&S.

Here's my stock answer…

SLR vs. P&S

"Single Lens Reflex" means that the camera has only one lens (which is true for almost all cameras these days anyhow) and the light follows a "reflex" or reflected path through the lens, through the camera and up to the viewfinder where you look when you compose your shot. Many years ago, there used to be a separate lens for the viewfinder and another one for exposing the film. These were called "Twin Lens Reflex" cameras. Hence the distinction of "SLR" came into being.

Today, an SLR still uses one lens for taking the picture, but the most important distinction is that the lens can be removed from the camera so that you can interchange lenses for different shooting situations, if you desire. For most casual photographers, one general purpose zoom lens will suffice most of the time, but you have the option of buying new lenses to give your camera different capabilities as your interests change.

A point-and-shoot (P&S) camera is set up so that you don't need to know much more than how to aim the camera (the "point" part) and press the button (the "shoot" part). While you can use pretty much any SLR in the same manner, this is almost the limit with many P&S cameras. The user can exercise a little control if desired, but it's usually easier just to stick to the automatic mode for 80-90% of your shots. P&S cameras do not have interchangeable lenses.

P&S cameras are generally a lot smaller than SLR's and many of them are small enough to fit into a shirt pocket with ease.

To ME, the major distinction between the two styles is the image quality. P&S cameras have much smaller sensors, which is where the camera captures the light to make the image. The larger the sensor, as a rule, the better the image quality. For a typical 4" x 6" print of the entire shot, this doesn't make a whole lot of difference, but if you want to make an enlargement of a portion of your picture, the SLR with its larger sensor will give a much better result. Most P&S cameras have a sensor that is only about 4 mm x 5 mm. A few have the larger 7 mm x 5 mm size. Most SLR sensors range from 14.8 mm x 22.2 mm to 15.5 mm x 23.6 mm. (There are some smaller and some larger, though.) This is about 10-to-20 times bigger than a P&S sensor.

Go here
and click on "All sizes" and then "Original" to see the difference. Read the text for more explanation.

Do the same for this pair of shots:

The first one is taken with a Canon Powershot SD900, which is a pretty darn good camera by P&S standards. The second one is taken with a Nikon D200, also a prety darn good camera by SLR standards, but it could have been done with almost any other SLR out there with similar results.

DSLR camera is 10 times more than the normal camera.

An SLR is a film camera; now seldom used apart from enthusiasts.
DSLR is a Digital SLR.
Works in the same sort of way except it captures a digital image instead of a film which has to be developed and printed.

Perhaps it is easier to understand that there are two types of cameras, film and digital. With film, the camera exposes the film, which is then developed at some lab and then printed. With digital, the camera exposes a sensor, which converts the light to electricity, which is then digitized (hence digital), and then saved to a file, which then can be printed.

Both forms, film and digital, can have SLR cameras. These are those big black cameras you see professional photographers (and others) carrying around or mounting on tripods. SLR usually refers to film SLR cameras, DSLR refers to the digital version of SLR cameras, the D standing for digital.

So, if you have a film camera, you can have the film developed and printed. If you have a digital camera, you can have the files printed.