Logs, logins and backlogs

It might sound like an obvious association to make but I doubt many people would connect the terms log files, backlog and login with a chunk of wood despite it being the most likely origin of these words.

To start at the beginning, the root of the word log meaning ‘a bulky mass of wood’ isn't entirely clear. One theory links it to the Swedish låga meaning ‘a fallen tree lying on the ground’ and phonetically it does sound similar. Another theory is that log and the related clog arose from attempts to evoke the sense of something large and heavy. While others have linked it to lug meaning ‘something heavy and clumsy’, from the Dutch word log meaning ‘slow and heavy’. Perhaps I'm barking up the wrong tree but I think there is probably a case for all three.

The opening line of every episode of Star Trek, “Captain’s log, stardate...”, is perhaps the most famous cultural reference that hints at how log might have drifted into the realm of technology. However the answer isn't space travel but rather the sea or to be more specific, sailing.

"Captain's log stardate XXX" was the opening line for every episode of Star Trek.

A captain's log, or simply a log, was a record of observations or readings that started life on the high seas, specifically as an apparatus used to measure the speed of a ship. Sailors would throw a wooden log or board tied to 150 fathom (900 ft) length of rope overboard and would time how long it took to run out.

These daily recordings of their ship’s speed were kept in a log-book, a term which can be traced back to the 1670s. To untangle the root of another word, sailors would also tie knots in the string tied to the log-line and by counting these knots, were able to give the ship a more precise measurement of speed: knots per hour.

An example of a log and line from the National Maritime Museum.

The log-book is the most logical (from the Greek logos meaning 'reason' - not the wooden log!) answer for how log came to mean a record of performance or progress in technology. The verb to log would arise in the 1880s, initially referring to the entry of a man's name into a log-book for some kind of offence. This would later migrate into computing in the 1960s in the form of login, the act involving a user entering their name to access a computer, as well as logging in and logging out.

The original backlog was a large log placed at the back of a fireplace.

The other type of log that relates to a physical wooden log but with a different origin is the term backlog, meaning an accumulation of uncompleted work or matters to be dealt with. The etymological root of this word lies in the fireplace. Simply put, a backlog was the large log placed at the back of the fire that was intended to "smoulder for days" from the 1680s. The term was later used figuratively to mean 'something in reserve, reserves or an accumulation' by the late 1800s before the meaning changing to 'an arrears of unfulfilled orders or uncompleted work' from the 1930s. So that is the reason we have backlogs but no frontlogs, which I'd imagine would be more prone to rolling out and setting fire to your carpet! 🔥