The technical meaning is a hardware or software set-up that translates between two dissimilar protocols, for example Prodigy has a gateway that translates between its internal, proprietary e-mail format and Internet e-mail format. Another, sloppier meaning of gateway is to describe any mechanism for providing access to another system.
E-Commerce applied to government. Government as both purchaser and seller.
Graphics Interchange Format. An image file format common on CompuServe and for small images on the Internet. It is limited to 256 colours but produces compact files. GIF's, in common with some other internet 'friendly' graphic formats, can be interleaved (allowing downloads in steps which provide increasing resolution with each step) and given a property known as 'transparency', which allows any background of the web page to be seen through the graphic, if required.