I got into a bit stuck on a question of wording at work and am hoping there are some English majors in here.

Basically, I'm trying to name someone who posts an ad online (think Craigslist).

We're hesitating between author and poster. I naturally used the term poster, but a colleague suggested author.

In French, you'd definitely use author, but I think in English, given the context, I think poster would make more sense.

This is a bit of stupid point to get stuck on, but it's eating me alive. Help...

Thinking about it:

poster seems really restricted to a message board: http://www.dictionary.com/browse/poster
while author seems to be more generic and not restricted to literary work: http://www.dictionary.com/browse/author

Internet comes to the rescue again... Same here, that's my gut instinct. Maybe its a part of the language where formal definition has not caught up to popular use.

It's a bit blurry. Formally, it seems author is better, but informally, I think poster is more natural to the mind of people who use the internet.

EDIT: Interestingly, informally at least, I think author has greater copyright implications than poster. I think poster should be all the more appropriate for an internet ad.