A block-oriented terminal is a type of computer terminal that communicates with its host in blocks of data, usually chunks of text, as opposed to a character-oriented terminal that communicates with its host one character at a time. The IBM 3270 is perhaps the most common implementation of a block-oriented terminal.
The host sends to the terminal a description of the fields to be displayed. The terminal processes and then displays the page. When the user submits data, like updates in a database entry, an entire field is sent to the host in one burst. This behavior has the advantage of causing less system load on the host and less network traffic than character-oriented terminals. They are also more responsive to the user, especially over slow connections, since editing within a field is done locally on the terminal itself.