Why you use your ‘logon’ to ‘log on’

It's all about the adverbs

Time to start work. So you “log on” to your computer, using your “logon” or “log-on,” or your user name.

The latter is a noun, the former a verb, and they have not yet fused into one word for both forms.
Here’s what The Associated Press Stylebook says:

login, logon, logoff (n.) But use as two words in verb form: I log in to my computer.

New words often come about when someone takes one form and starts using it another way, called a “back-formation.” Sometimes the noun leads the way: “Target,” for example, was acceptable only a noun as recently as the 1964 printing of the first edition of Webster’s New World College Dictionary. In the case of “log on,” the verb came before the noun.

Although “on” is often a preposition, in the verb “log on,” it’s an adverb. You wouldn’t say “I’m going to log the computer” unless you’re putting the computer on a list; the “on” is necessary to further explain the action. Another way to understand this is to make the verb another tense. Today you “log on,” but yesterday you “logged on.” No one is suggesting that this become “loggedon.” Yet.

If you add another preposition, by the way, it changes nothing: You still “log on to” your computer, not “log onto.” “Log” still needs its adverb, and “onto” and “into” are prepositions.

For now, the adverb “in” or “on” is separate in most dictionaries as well as in style and usage guides. But it’s likely to close ranks before too long, in present and future tense, at least, as ubiquitous terms have a habit of doing (see “online”). The trend is often accelerated when noun and verb forms differ; it’s so much easier to just write “underway” than to try to figure out what part of speech you’re using.

The noun, arriving later, is still struggling with different forms. Many people involved in the computer and tech industry already use “logon” as both noun and verb, but there’s no outside consensus yet. While the hyphen-averse AP has gone with one word, its dictionary, WWN5, has no noun forms. Merriam-Webster’s Dictionary prefers “log-on” and “log-in,” while the American Heritage Dictionary sides with the AP.

A similar thing has happened with another recent back-formation, for a new company. It’s a “startup” in the AP stylebook, even though WWN5, M-W, and AmHer prefer “start-up.” What it does, though, is “start up.” That adverb again.

What’s the difference between “logging in” and “logging on”? Most dictionaries view them as synonyms, favoring the “on” form, even though it’s newer than the “in” form. (M-W traces “log in” to 1962 and “log on” to 1977; The Oxford English Dictionary traces “log in” to 1963. For many people, though, there’s a subtle distinction. Just as one has to go through a surface to get to the inside, some view “logging on” as an initial, broader act. Once “logged on” to a computer or network, they want to “log in” to a particular site or area of the network.

For most people, though, the distinction doesn’t matter as long as they remember all their passwords.

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.