Complex sentence: Related but distinct, is the historical practice of using abbreviations and code words to compress the meaning of phrases into a small set of characters for ease of transmission over a telegraph, a device for transmitting electrical impulses used for communications, introduced from 1839 onwards.
Split into simpler sentences: Related but distinct, is the historical practice of using abbreviations and code word to compress the meaning of phrases into a small set of characters for ease of transmission over a telegraph. Coded telegraph expressions arose out of the use of the telegraph, a device for transmitting electrical impulses used for communications, introduced from 1839 onwards.