A point-and-shoot is a camera which takes an adequately exposed and focused picture, under typical conditions, by pointing the camera at the subject and shooting the picture by pressing the shutter button. Hence, the term point-and-shoot.

Technically, nearly all modern digital cameras fit that description. So most people use this term to mean strictly point-and-shoot: a camera on which you cannot directly set the primary photographic controls of aperture and shutter-speed. Note that most such modern cameras offer some controls, such as ISO speed, flash mode, drive mode and even white-balance.

Frequently people use the term point-and-shoot to mean a camera which is not a DSLR. The term DSLR is described under the title SLR, below.

Point-and-shoot digital cameras are generally small, falling into either the ultra-compact or compact size. The most likely reason is that manufacturers see larger cameras as more appealing to advanced users who would demand photographic control. Still, manufacturers include a point-and-shoot mode on all but a few professional cameras.

The terms prosumer-camera and bridge-camera are used to describe advanced digital cameras with complete manual controls and high-quality fixed lenses.

The word prosumer is a contraction of professional and consumer, signifying someone in between. The word bridge evokes the same idea as something in between.

The term all-in-one signifies a camera who's lens is attached to the body even though batteries and memory are normally interchangeable.

All-in-one is also frequently used to described any non-SLR camera with advanced features such as a prosumer digital camera.

Prosumer cameras have both an LCD and a viewfinder. An EVF is typical for such cameras when it has either a long zoom or a very wide-angle lens. This provides more accurate framing which is important for advanced users.

SLR stands for Single Lens Reflex. It means a camera which has a single lens where incoming light is reflected into the viewfinder. This is in contrast with a camera having two lenses, with the second one being used for the viewfinder only. A digital SLR is called a DSLR.

The terms SLR and DSLR are probably the most standard terminology because of their obvious definition. By their reflex nature, all SLR cameras have an optical viewfinder (OVF). The view from the OVF corresponds to view from the lens except for some slight cropping.

Full-frame cameras are DLSR cameras whose sensor is the same size as 35mm film. These cameras can use lenses made for 35mm film cameras and the result will be an identical field-of-view.

Most people are right to disagree that an EVF camera is an SLR camera since light is not reflected to the viewfinder. However, some stores list such prosumer cameras under the SLR category, perhaps because of they resemblance.

Even though the term SLR does not imply anything else, all current DSLR cameras have interchangeable lenses and full-manual controls. This was not always the case, as there was a fixed-lens SLR camera from HP. Since reflex optics and interchangeable lens systems take space, DSLR cameras are among the largest digital cameras.

A medium-format camera, as opposed to a medium-size camera, has a sensor which is larger than a full-frame sensor. The name comes from film sizes where medium-format films are larger are larger than 35mm films.

Just like digital cameras accepting lenses designed for 35mm film cameras, medium-format digital cameras have a focal-length multiplication (FLM) factor. Since there are several sizes of medium-format films, the FLM will depend on the medium-format being compared.

Digital medium-format photography can be made using a medium-format digital camera back or a medium-format digital camera. As a back, the digital camera is inserted at the back of a medium-format film camera. As a camera, digital medium-format can be just a big SLR, complete with reflex viewfinder. A tethered camera must be attached to a computer or other storage device to operate. An un-tethered camera can be used just like a DSLR.

These are presently very expensive cameras designed for use by photography professionals. Lenses for 35mm film cameras won't work on these cameras. The advantage of digital medium-format. Medium-format can boast upwards of 45 megapixels while maintaining low image-noise. Hence, such cameras are used for very large imagery.

An Interchangeable Lens Camera (ILC) is a camera with an interchangeable lens. The field-of-view and optical zoom of such an ILC depends on the lens attached to it.

The term Fixed-Lens Camera (FLC) is used to describe all cameras with lenses that cannot be removed. Since their lens is fixed, FLC have a given 35mm equivalent focal-length range. However, conversion lenses can sometimes be added to widen or narrow their field-of-view.

Technically, most types of cameras can be made as ILC or FLC, even DSLR cameras. However, since having an interchangeable lens is considered an advanced feature, all current DSLR cameras are ILC and vice-versa. While there was a DSLR FLC a few years ago, the future is likely to offer a non-SLR ILC with an EVF for viewfinder in addition to a live-preview LCD.

In terms of flexibility, interchangeable lenses are unsurpassed. There are hundreds of lenses available, covering ultra-wide to super-telephoto, including fish-eye, tilt-shift lenses and lens sizes that would not be practical otherwise. The price of ILC is the potential for getting dust on the sensor, a problem which so far only Olympus has addressed.

On a FLC, certain conversion lenses may be available, but most turn the camera into a fixed-focal length camera and diminish the image quality with additional lens elements in the optical path.

A display, LCD or EVF, previewing the picture before it is taken, is called a live-view. The term live-view camera is sometimes used to describe a camera showing a live-view. It turns out that all camera types can have a live-view, but it is much harder for DSLR cameras because the reflex mirror is in the optical path to the sensor. Also large sensors common in DSLR cameras consume more power and generate more heat than smaller sensors common in live-view cameras.

Digicam is short for digital camera, but some people use this term pejoratively to describe non-DSLR cameras. In summary, even though most terms have clear definitions, they are frequently used in broader ways.

The types listed above are not exclusive and some types go hand-in-hand. For example, all point-and-shoot cameras are fixed-lens cameras. Some types are unlikely to be seen together, such as a point-and-shoot medium-format, which would be unlikely to find any buyers.

The Olympus E-10 and E-20 were among the first two DSLR cameras with live-view. They used a beam-splitter to transmit light to the sensor and the optical viewfinder simultaneously. Fuji's S3 Pro incorporates a mirror-lockup mode with a back and white live-view usable for up to 30 seconds.

Recently, Olympus announced the E-330 which will have the least limited live-view available on a DSLR. Its live-view will be useful for approximately framing subjects at odd angles. Even with this advancement, the E-330's live-view modes will either show 100% frame coverage but disable auto-focus or will show 92% frame coverage with auto-focus enabled. This live-view will neither show proper exposure nor proper white-balance, so its usefulness will be limited compared to true live-view, but this is a welcome step towards a true live-view DSLR.