Your question might lead to several philosophical discussions, because it is not at all specific. So, it is not easy to try to use proper definitions without a minimum context to focus on. Anyway, I'll try. A picture is a general term for a visual representation of something. A picture, by this definition, has to contain both aspects: it must be a representation, and it must be visual. A bitmap, by itself, will not be a picture. It will just be a sequence of bits. It will become a picture when you display it on a screen, or when you print it on a piece of paper, or when you make it visible in any way. So, generally speaking, a bitmap is a way to store image data, so that it can be represented as a picture (when used by a display device). Note that so do JPEG, TIFF, GIF, PNG, and many more image data storage formats. None of them are pictures until they are displayed. Most often with computers the term bitmap is used to refer to the storage of picture data without compression. In this form, there is a data unit for each pixel. For example, an RGB bitmap will contain 3 bytes for each pixel. In a 6 mega-pixel image from your digital camera the bitmap would then have 18 MB in size. The general oposite of using the term bitmap is usually to refer to compressed images. In these formats, a data unit is used to represent a larger number of pixels. For example, a high quality JPEG would typicall have 0.3 bytes per pixel (about 10 times less than bitmaps). By allowing JPEG compression to discard more and more information then you can have as few as 0.06 bytes per pixel (a single byte will generate enough information to draw more than 16 pixels) and you may still recognize the picture it intends to represent. There are also, of course, lossless compression formats. To back this up here are google's definitions: define:picture - a visual representation (of an object or scene or person or abstraction) produced on a surface; "they showed us the pictures of their wedding"; "a movie is a series of images projected so rapidly that the eye integrates them" define:bitmap - The method of storing information that maps an image pixel, bit by bit. There are many bitmapped file formats, .bmp, .pcx, .pict, .pict-2, tiff, .tif, .gif (89a), and so on. Most image files are bit mapped. This type of file gives you the ´jaggies´, when examined closely you can see the line of pixels that create edges. Bitmap images are used by all computers. The desktop or screen information for all Windows machines uses .bmp files, while