Like many professions, sports and hobbies, photography has gradually developed it's own terminology and jargon. Maybe it's impossible to avoid, that nicknames get used and then start to spread and become standards. The language is handy if you want to sound like a photographer (although I'm not sure why you would), but also sometimes essential in understanding the technical concepts that are fundamental to the craft. To help, here are the most common terms that you might come across, and what they mean.
Aperture - How wide the shutter opens when you take a photo. A wider aperture means more light and less depth of field (i.e. less of the image in focus). The numbers work like fractions, so f/1.8 is a relatively large aperture and f/18 is relatively small.
Aspect Ratio - The proportions of an image. So a 3:2 image might be printed at 60cm x 40cm for example. Common rations are 16:9, 7:5, 3:2 and 1:1 (square).
AWB (Auto White Balance) - Allows the camera to control the coloration of the image.
Blownout - When part of an image appears as pure white, with any details lost. This is most common in a bright sky, but can happen if any part of the image is over-exposed.
Bokeh - A Japanese term referring to the patterns in the out-of-focus areas of an image, such as the circles created from spots of light.
Bracketing - A camera mode where the camera takes multiple images (usually 3 or 5), at different settings. Exposure bracketing is commonly used for HDR images when 3 or 5 images are taken, each at a different exposure, and later combined into one image.
Bridge Camera - Seen as a stepping stone between a point-and-shoot camera and a DSLR, in both size as capabilities. Typically incorporate a long zoom range but a relatively small sensor.
Burn - Dodge and Burn are terms used most commonly in film processing, to adjust the brightness of a part of a photo during the printing process. Burn makes an area of the photo darker.
Camera Shake - When slight unintentional movements of the camera cause the image to be blurred. This can be reduced or rectified by using a faster shutter speed, image stabilisation, a tripod, or by changing how the camera is held (e.g. a camera held at arms-length is less stable than with elbows tucked into the body).
Chimping - A slang term for the act of looking back at each photo on the camera screen after you've taken it. Rumour has it that the name comes from a tendency to make 'ooh, ooh' noises like a chimp at the sighting of a decent-looking photo.
Crop factor - Digital sensors smaller than 35mm are considered to be crop sensors. For any given lens, a smaller sensor will capture proportionally less of an image, so gives the appearance of magnification. Common sensor sizes are APS-C (in many DSLRs, Fujifilm, Sony and Samsung cameras) and Micro-Four-Thirds (Olympus and Panasonic).
CSC (Compact System Camera) - A mirrorless camera with interchangeable lenses that is typically smaller than a DSLR.
Depth of Field - The amount of a photo that is in focus, or more specifically the range of distances from the camera where any objects will be in focus. Controlled by changing the aperture.
DNG (Digital Negative) - DNG is a file type, like RAW and JPEG, created by Adobe. It offers similar characteristics to a RAW file without being specific to one camera manufacturer.
Dodge - Dodge and Burn are terms used most commonly in film processing, to adjust the brightness of a part of a photo during the printing process. Dodge makes an area of the photo lighter.
DPI (Dots per Inch) - The resolution (and hence, to an extent, quality) of an image or print. Calculated by dividing the size of the image (in pixels) by the print size. So if your image size is 3000x2000 and you want to print at 6x4 inches, the DPI is 3000/6 = 500. 300DPI is a good general target, but there are notable exceptions (such as billboards) when a much lower DPI is perfectly acceptable.
DSLR (Digital Single Lens Reflex) - A common type of camera that uses a combination of mirrors to present the view from the lens through an optical viewfinder. Most commonly produced by Canon, Nikon and Pentax.
EVF (Electronic Viewfinder) - An alternative to an optical viewfinder, an EVF uses a small electronic screen to show the view from the camera lens. The big advantage of an EVF is that it can show the effect of your camera settings as you change them, before taking the photo.
Exposure - The level of brightness/darkness of the resulting image. Controlled by Aperture, Shutter Speed and ISO settings.
Focal Length - Technically it's the distance from the optical centre of a lens to the camera's sensor. In practice this is the amount of magnification of the lens. For example, a 200mm lens gives a much longer focal length and magnification than a 50mm lens.
F-Stop - The f-stop or f-number is the measure of the size of aperture being used. e.g. f/1.8
Full-frame - A camera with a 35mm-sized sensor. A smaller sensor is considered to be a 'crop sensor'.
Glass - A lens or lenses. A variation on the theme, 'fast glass' refers to lenses with wide aperture settings such as f/1.4 or wider.
Grain - Grain is result of using high ISO film that creates slight variations instead of a consistent tone. In digital photography, 'noise' is a more accurate term and is generally less visually pleasing, but the cause is the same.
HDR (High Dynamic Range) - The intention of HDR is to overcome the dynamic limitations of image capture by techniques such as combining multiple images into one. A common example is to keep the details of a bright sky without making the ground subjects too dark. HDR techniques have developed into their own style of dramatic and heavily processed images.
IS (Image Stabilisation) - A function on the camera or lens that will attempt to reduce or counteract vibrations that could make your photo blurry. Turn it off if you're using a tripod.
ISO - For a film camera, ISO is the sensitivity of the film being used. In a digital camera, it's a setting for the sensitivity of the sensor. Low ISO (e.g. 100 or 200) is higher quality, higher ISO settings are typically used for low light situations.
JPEG - The most common type of image format. Most cameras have the option to produce RAW files, or JPEG files or both. Generating a JPEG means that the camera performs the processing necessary to produce a 'finished' image. Smaller in size and contain less information for later processing than a RAW file.
Megapixels - How many tiny single points of information the camera sensor can capture. More isn't necessarily better. Typically, more pixels will show more detail but be less effective in low light situations because each pixel is smaller.
Metering - The metering mode tells the camera which point (or points) on the image to use to determine exposure. Cameras typically offer at least a few different metering modes, such as spot metering (using one specific point) and centre-weighted metering (uses an average, but determined mostly by the centre of the image) and matrix metering (analyses the whole image).
Mirrorless - A camera that uses an electronic viewfinder or just the rear screen so doesn't requite the mirrors that a DSLR uses for it's optical viewfinder.
Moiré - A secondary pattern, usually unwanted, that can appear in a digital image with rapidly repeating lines or patterns.
Noise - The digital version of grain, when high ISO settings introduce small variations into what should be a consistent tone in an image.
Pancake lens - A lens that is thin in it's physical size.
Panning - The act of turning the camera to follow a moving subject with the aim of blurring the background whilst freezing the subject in the image.
Pixel - One single dot in an image, and the usual measure of the size of a digital image. e.g. 4000x3000 pixels.
Pixel Peeping - A slang term for looking at tiny details in an image, often with the aim of comparing the quality of one piece of equipment to another.
Point and Shoot camera - Usually a relatively small and simple camera, typically with a small sensor and limited manual controls.
Prime lens - A lens with a fixed focal length, as opposed to a zoom lens. Typically offer superior quality to an equivalent zoom lens.
RAW - A digital image file type that is specific to each camera manufacturer. Most cameras have the option in your camera to produce RAW files, or JPEG files or both. Generating a RAW file means that the camera doesn't perform the final processing to produce a 'finished' image - that processing (the RAW conversion) is performed in software such as Adobe Lightroom. Larger in size than JPEG files.
Sensor Size - The light sensitive area that is exposed to generate the image in a digital camera. A larger sensor can either accommodate more pixels, or allow more light to fall on each pixel.
Shutter - The mechanism that opens and closes to let light onto the camera's sensor or film.
Shutter Release Cable - A cable for remote operation of the shutter. One common use is to prevent unwanted vibrations when using a tripod and slow shutter speeds.
Shutter Speed - The time the the shutter remains open during the capture of an image.
Stops - A stop of light is a halving or doubling in the exposure of the image, either by a change in aperture, shutter speed or ISO. Doubling or halving the ISO setting is a change of one stop. The same goes for shutter speed. Aperture is more complicated, with each step in the following sequence representing one stop: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8.
Thumbnails - A small representation of an image.
TTL (Through the lens) - A method for automatically controlling the power of a flash.
Viewfinder - The small viewing window for framing the image as an alternative to the rear screen. Can be electronic (EVF) or optical (OVF).
Vignette - A darkening of the edges of an image. Occurs naturally in some lenses, and is often applied in post-processing to guide the attention of the viewer to the centre of the image.
White Balance - The coloration of the image as effected by both natural and artificial light, so a neutral color (white or grey) may not appear as neutral in the resulting image.
Zoom lens - A lens that offers a variety of focal lengths, as opposed to a fixed or prime lens.