25. A method for compressing data by reducing the number of binary bits required to represent the data comprising: storing each of a plurality of selected units of a set of units in unit positions to form a library, each unit position having a memory address expressed in bits, detecting each unit in the data and searching the memory to determine if the respective unit is in the library, and alternatively compiling data representative of the units which are not stored in the memory library or the addresses of the units which are stored in the memory library together with a code indicating which alternative is compiled in each instance.
25. A method for compressing data by reducing the number of binary bits required to represent the data comprising: storing each of a plurality of selected units of a set of units in unit positions to form a library, each unit position having a memory address expressed in bits, detecting each unit in the data and searching the memory to determine if the respective unit is in the library, and alternatively compiling data representative of the units which are not stored in the memory library or the addresses of the units which are stored in the memory library together with a code indicating which alternative is compiled in each instance. 26. The method of claim 25 wherein: each unit of data is representative of a word in a textual message, each word is comprised of two or more characters, and each character is represented by a predetermined number of binary bits.