Animated GIF
A GIF graphic file, which consists of two or more images shown in a timed sequence to give the effect of motion. - Example -

Anti-Aliasing
Smoothing or blending the transition of pixels in an image. Anti-aliasing the edges on a graphic image makes the edges appear smooth, not jagged.
- Example -

Bitmap image
An image with 1 bit of color information per pixel, also known as a bitmapped image. The only colors displayed in a bitmapped image are black and white. JPEG, GIF and TIFF are both bitmap formats.
- Example -

Compression/Decompression
The reduction of image file size for processing, storage, and transmission. The quality of the image may be affected by the compression. There are two types of compression:
Lossless compression
is a process that reduces the storage space needed for an image file without loss of data. If an image has undergone lossless compression, it will be identical to the image before it was compressed.
Lossy compression
is a process that reduces the storage space by discarding information (information that is "redundant" and not perceptible to the human eye). If an image that has undergone lossy compression is decompressed, it will differ form the image before it was compressed, even though the difference may be difficult for the human eye to detect.

CMYK
The four process colors used in printing:
cyan, magenta, yellow, and black

Dots per inch (dpi)
Dots per inch: a measure of image resolution.

File Size
The file size of an image is proportional to its resolution. The higher the resolution, the bigger the file size. File size is different from image size.

GIF
Graphic Image File Format. Support only 256 colors, best format for vector and clipart.

Image size
Describes the actual physical dimensions of an image.

JPEG
Joint Photographic Experts Group. A lossy compression algorithm for condensing the size of image files. Support up to millions of colors. Best format for photograph or image with gradient colors.

Pixel
Often referred to as dot, as in "dots per inch". A single dot on a computer display or in a digital image.

Resolution
The number of pixels per inch in an image, or the number of dots per inch used by an output device.

RGB
Red, green, and blue; RGB is the basic additive color model used for any computer monitor.

TIFF
Tagged Image/Interchange File Format. A file storage format implemented on a wide variety of computer systems, usually used for archival scans.