no, you can't manually add item types.
In general, you only need an item type where different citations are required - which I'd doubt is the case for an ad - instead, categorize it by the medium it's in - a newspaper or magazine article, a radio or TV broadcast, an "artwork" (e.g. a photo taken of an ad on a street) etc.
The Ads were items found on the Web in places such as Craigslist and JournalismJobs.com. You wouldn't call them Forum posts. What are they? Also, if I read the New York Times online, I can still cite the article as a newspaper article. But what if you have an article that is written online, for a site that has no print analog? Are they still called magazine articles?
those are judgment calls - the same type of calls you'd have to make if you were going to write a bibliography by hand. I would only call something a magazine article when it's actually published in a volume - regardless of whether that volume is online only or not. E.g. blogpost up at NYTs or the like are, to me, webpages/blogposts.
I'd call a craigslist ad a forum post (internally I don't think that's distinguished from a webpage, so don't worry about terminology too much).
Again, Zotero categories are mainly bibliographical, not categorical. As you get into a subject matter, there are dozens, maybe hundreds of distinctions that you can make about item types. You can make those in your own database with tags, collections etc. but they're not of bibliographical relevance.
I have used Zotero to cite advertisements but there are so many issues I have always felt the need to do a great deal of hand editing of the final document after the Zotero reference marks have been removed.
None of the style guides (APA, CMoS, etc.) seem to have a standard for ads.
When writing about the culture of recreational risk-taking I find that ads can be enlightening.
For the Web ads I put something like the following in the title field of the Zotero webpage item:
Advertisement for: product, company, (ad-serving or -management company); With: ArticleTitle
Advertisement for: Sonicare, Philips, (DoubleClick); With: "Some hard lessons about college costs"
I also grab and keep a snapshot or screen capture. The ads that accompany any web page are likely to be different depending upon a viewer's browsing history or some other variable.
Printed sources, such as magazines, are often regionally distributed with different ads for different regions, different ads for mailed subscriptions vs. store-bought issues, etc. In my experience, the article pagination is usually stable across versions but not always.
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In general, you only need an item type where different citations are required - which I'd doubt is the case for an ad - instead, categorize it by the medium it's in - a newspaper or magazine article, a radio or TV broadcast, an "artwork" (e.g. a photo taken of an ad on a street) etc.
For organizing items use tags and/or collections.
I would only call something a magazine article when it's actually published in a volume - regardless of whether that volume is online only or not. E.g. blogpost up at NYTs or the like are, to me, webpages/blogposts.
I'd call a craigslist ad a forum post (internally I don't think that's distinguished from a webpage, so don't worry about terminology too much).
Again, Zotero categories are mainly bibliographical, not categorical. As you get into a subject matter, there are dozens, maybe hundreds of distinctions that you can make about item types. You can make those in your own database with tags, collections etc. but they're not of bibliographical relevance.
None of the style guides (APA, CMoS, etc.) seem to have a standard for ads.
When writing about the culture of recreational risk-taking I find that ads can be enlightening.
For the Web ads I put something like the following in the title field of the Zotero webpage item:
Advertisement for: product, company, (ad-serving or -management company); With: ArticleTitle
Advertisement for: Sonicare, Philips, (DoubleClick); With: "Some hard lessons about college costs"
I also grab and keep a snapshot or screen capture. The ads that accompany any web page are likely to be different depending upon a viewer's browsing history or some other variable.
Printed sources, such as magazines, are often regionally distributed with different ads for different regions, different ads for mailed subscriptions vs. store-bought issues, etc. In my experience, the article pagination is usually stable across versions but not always.