The secret origin of “log in”

We do it dozens of times a day, every day, but why do we call it logging in?

“Log in” is one of those phrases that sounds weirder the more you say it. It’s ubiquitous in online life, though it does seem like it’s being slowly overtaken by “sign in” [note 1]. But where does the phrase come from in the first place?

Clearly, a job for the Oxford English Dictionary. Luckily you can usually access the online OED through your local public library site. Thanks, libraries!

Representative terminal, not actually a CTSS terminal, CC LevitateMe

The OED’s earliest listed usage of “log in” in the modern sense of “to open one’s on-line access to a computer” is from the 1963 publication Compatible Time-Sharing System from the MIT Computation Center. [2]  I’m not sure if this is truly the first usage of “log in”, but it would make sense if it was, as CTSS, started in 1961, was arguably the first time-sharing operating systems, and so possibly the first system that you needed to log in to. (Before that we only had batch processing systems).

Whether it was CTSS or a similar system, I envision an engineer, probably at MIT, somewhere between 1959 and 1961, needing to describe a new user command for the system they were creating.We get a lot of neologisms from these situations, and it’s very possible log in dates from just this moment in history.

CTSS Timeshare: A Programmer’s Guide, MIT press

It’s also possible that “log in” was used in a non-computer sense before time-share systems, but I haven’t seen it in print. But of course the “log” part, meaning to record something or someone, predates computers by hundreds of years.

Ship’s log CC David Churbuck

That usage is in turn a shortening from entering something into a “log-book”, or ship’s log, (or captain’s log, if you’re in Starfleet) which the OED defines as:

A book in which the particulars of a ship’s voyage (including her rate of progress as indicated by the log) are entered daily from the log-board.

The first listed usage of log-book or  logbook is from roughly 1689 ( J. Moore’s  New Syst. Math). By travelling back 250 years in time, we’ve gone from identifying ourselves within a computer system to entering the speed of a sailing ship into a book.

But why was it called a logbook? Because of this apparatus here, variously called a chip log, ship log, or log:

Chip log log line, & reel, CC Kate’s Photo Diary

A log! Or at least, a piece of heavy wood, attached to a knotted rope. Which you throw overboard and time how many knots go by for a set period of time, or, as Wikipedia describes it:

When the navigator wished to determine the speed of his vessel, a sailor dropped the log over the stern of the ship. The log would act as a drogue and remain roughly in place while the vessel moved away. The log-line was allowed to run out for a fixed period of time. The speed of the ship was indicated by the length of log-line passing over the stern during that time.

This is also why we still measure nautical speed in knots. So, when you next log in to Facebook or Gmail, think about big hunks of wood being thrown off the side of a ship to measure speed.

P.S. This was fun and entertaining for me to put together, but I’m sure there are holes and inaccuracies. If you know more about the origins of “log in”, please chime in with comments, and I’ll update accordingly!

Update 8/6/11: In a comment, Andrew Durdin points to some non-computer uses of “log in” from the 1950s. Awesome!

Note 1:  A couple of years ago I did a survey of top websites in the US and UK and whether they used “sign in”, “log in”, “login”, “log on”, or some other variant. The answer at the time seemed to be that if you combined “log in” and “login”, it exceeded “sign in”, but not by much. I’ve also noticed that the trend toward “sign in” is increasing, especially with the most popular services. Facebook seems to be a “log in” hold-out. Login_survey

If the whole “sign in” vs. log in” debate is interesting to you, there are some debates here and here. My personal feeling is that either is fine, but “sign in” is marginally more friendly and probably the preferred usage, though I’ll miss the nautical association. On the other hand, I feel strongly that “login” as a verb is an abomination and not to be tolerated under any circumstances.

If you’re really interested, you might start noticing where sites show their own evolutions and inconsistencies of usage. For example, Twitter’s web UI uses “sign in” but the URL says “login”. But now we’re probably reaching the outer limits of obsession and should stop.

Note 2. Here’s a PDF of a CTSS manual from 1964. There’s an underlined “log in” on page 6.
Interestingly, CTSS is also the system that gave us the first email system, as described by Errol Morris in his history of his brother’s role in the creation of that system. The Wikipedia history of CTSS is pretty fascinating stuff as well, and contains links to oral histories of the creation of CTSS and Multics (the precursor to Unix).




14 thoughts on “The secret origin of “log in”

  1. “It’s also possible that “log in” was used in a non-computer sense before time-share systems, but I haven’t seen it in print.”
    It was, and the sense is very similar, but less specific and less fixed than the computer sense we are familiar with. The connection is from a ‘log’—the record of events occurring—and ‘log … in’ meaning to record an event in this log:
    “Every phone call, every brief visit by a client, every moment spent was logged in.” ABA Journal, Jul 1956 —
    “The PBY message had been logged in at 7” LIFE, Dec 3, 1956 —
    This usage naturally extended to recording the arrival and departure of persons from controlled spaces:
    “Mr. Eisenhower was logged in at LaGuardia at 6:55 P.M.” The New Yorker, Volume 34, 1958 —
    “Culombe was logged in at the jail between 8 and 9 that night.” United States Supreme Court reports, Volume 6, 1960 —
    I could only find one occurrence of “logged out” to mean making a record of departure (out of three hits for “logged out at”):
    “The Victory left at 3:15 am EST on Saturday, October 1, and the White was logged out at 3:30 am.” Skillings’ mining review, Volume 44, 1955 —
    With a little more searching, I hit the jackpot:
    “Customers log in and out on a time clock.” Data processing digest, Volume 6, 1960 —
    This shows that “log in” and “log out” were used more or less synonymously with the more common “clock in” and “clock out”, referring to timekeeping. More importantly, it shows the syntactic shift from *“the attendant logged in the customer” to *“the customer logged in” in the case where the log-keeping mechanism is automated, and operated by the person arriving or departing.

  2. The story about the ship also relates to “blog”, a “book” where daily experiences are narrated. Earlier in time it was the captain describing the trip. Now it’s people talking about their cats.
    In fact, in 2004/2005, there were many blogs that instead of “blog” were called something else which right now I can’t remember. It was 2 words “b…..” and “log”.
    Maybe in terms of the time-sharing system, the reason to use the term “login” is not so much to mean “entering a computer system” but to “log” the beginning and the ending of the usage of the system, like at a factory with an old check-in/out card.

  3. Andrew: that’s wonderful! I’ll update the post accordingly. I’d seen pretty early references to “logging” someone (often putting them down on a list for punishment), but your finds are spot on.

  4. It’s so funny to me that you guys see this is a revelation. I have *always* thought that ‘log on’ and ‘log off’ referred to some archaic practice where you documented the start and end time of your session, probably for billing purposes. That is, you ‘log the time you got on’ and ‘log the time you got off’. Shows how unobvious some obvious things can be.

  5. I prefer “log in” to “sign in” as “sign in” is very similar to “sign up” which some sites use instead of “register”. For non-native English speakers, the difference between “sign in” and “sign up” is subtle and may require conscious thought (as in my case) or be lost entirely.

    Use “log in” and “register” for international audiences.

  6. @Blah: “Blog” is an abbreviated form of the portmanteau of “web” and “log”: “weblog”. That’s it. It’s not even that old.

  7. But if schools are no longer teaching cursive handwritting, is the phrase ‘sign in’ also anachronistic? Especially on a computer… with a keyboard?

  8. On the University of Michigan Timesharing System in the 70’s, users had an account with a monetary value which decreased as they used the system. You couldn’t $signin without money.

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