A carousel “rotates” content panes automatically after time-out, cycling through images or other content that has the same display size. Sometimes a carousel is (ambigously and/or erroneously) called a slider (such as on Wikia).
It is useful mostly to tell upper-level management that their content is “on the homepage” (which is where carousels nearly invariably appear) while not wasting much space or actually causing many users to notice it (YMMV).
Don’t call it a “slider”Edit
A disturbing trend among the more ignorant members of the web design/development community is to call carousels “sliders” or “image sliders.” This is dangerous, as Alan Hogan asserts:
- Things that show a series of images are called carousels (because they rotate!). And what if your “slider” (carousel) fades instead of transitioning with a horizontal wipe? Not sliding then! Sliders are things you drag and drop to select a value within a range (like a volume slider).
- Had not seen carousels called “sliders” until two days ago […].
- Please also note that both Bootstrap and YUI call this pattern a “carousel,” and some of the most popular jQuery plugins do, as well.
Language and clarity matter! A Slider is a thing already, so let’s avoid overloading terms when we can help it.
Novelty site ShouldIUseACarousel.com, from Jared W. Smith, asserts so.
He quotes experts in this assertion:
“Almost all of the testing I’ve managed has proven content delivered via carousels to be missed by users. Few interact with them.”
The target was the biggest item on the homepage - the first carousel item. “Nonetheless, the user failed the task.” — Nielsen Norman Groupnielsen norman Group
“We have tested rotating offers many times and have found it to be a poor way of presenting home page content.”
— wider funnel