Hello, I'm Mervi!
An artist, nerd and business sorcerer, dedicated to make world more beautiful and strange with art, illustrations and logos + to help you figure your sustainable business out.
Browsing around websites, especially commercial kind, you are likely to see sliders, carousels, rotators. They are those areas which have usually images, sometimes text and the content rotates automatically. Sliders are most often used to promote the website owner's skills, services of the company or the products of a web store. I think sliders are a really bad idea and they are most often used for all the wrong reasons.
As with any content that relies on images, sliders create issues with accessibility. Especially for people with any scale of blindness a thousand words is worth more than a picture. Sliders add an extra problem, because it can be confusing to browse a site with a screen reader when the content keeps switching in short periods. Sliders also are often poorly structured and configured. They may include multiple h1-elements, the main heading elements, when a page on a website is supposed to have only one of them. The time a slide is shown can be too short for someone who reads slowly or for a screen reader, and even a slower slider takes certain control out of the users hands. For users with motor skill issues the automatically moving sliders provide a huge problem too. Now you see it, now you don't!
Sliders are really hard to make work on responsive and mobile sites. Yes, there are sliders which are created to work with responsive, but even they come with issues. They can get stuck or be sluggish and the slider content may not work very well on a smaller screen. A slider is always a wild card with responsive and mobile design. There are so many things that can go wrong. The scripts may not be loading fast enough, the slider controls can be hard to use with a touch screen and scrolling a site with a slider is always like trying to drive between those orange cones. "Whoops, did I really click that?" When you are going to have a responsive or mobile website it's the safest bet to steer clear from sliders. And because the mobile web usage is continuously growing, sliders are getting more and more difficult.
In SEO point of view sliders are also a bad idea. Actually anything that messes with usability and accessibility is bad for SEO. As mentioned above the poorly structured and configured sliders can present the search engines with too many h1-elements. It is the (textual) content is what gives search engines the searchable content. Sliders often have very shallow text content if any thus they don't give search engines any or very much keywords or content to search for. Additionally sliders have a tendency to slow your website down. This is a problem when search engines such as Google penalise websites for being slow. If a slider slows your website down it makes Google push it lower in search results in favour of faster sites.
A slider also has a tendency to push important content below fold. This means the important content below your slider is pushed downwards so that it's not shown on the page without scrolling. Okay, I do remind everyone all the time that people are quite capable of scrolling. But search engines do see the top of your page as the most relevant content and lower sides as least relevant. Thus from a SEO point of view pushing the important, keyword rich content downwards is a pretty stupid idea.
Some people think sliders are good for conversions. With a slider you can promote the important contents, for instance some selected products in your store and people will click and buy immediately. Funny thing is that sliders actually very rarely help with conversions. For the previous reasons they may make your site hard to use and harder to find, but there are other reasons why a slider doesn't sell.
A slider can cause or be a victim of banner blindness. Banner blindness is that thing when you kind of see a banner on a website but decide more or less consciously to ignore it, because it seems like an advertisement to you. Sliders, especially because they present movement like many banner ads, are a very common case of banner blindness. Banner ads on websites are generally not working very well and because that slider does look like an ad to your website users they are going to ignore it. Jacob Nielsen, a well known usability researcher and advocate has proved that auto-rotating carousels annoy users and reduce visibility of the important content.
The sliders were also tested at the website of University of Notre Dame. The statistics revealed that the first slide of a slider gained almost all of the clicks and only about 1% of website visitors were clicking the slides. Because of these reasons most sliders end up being a pretty useless part of a website. It doesn't draw clicks, it doesn't create sales and it can even hide content from website users and annoy them.
The first thing to ask when you think about adding a slider to a website is what value does it add to the site. If you have to think about this really hard, that's your answer. There's no value. In most cases sliders are added because "they look cool". That's not really adding any value to your site, unless the only reason for your site to exist is to look cool. Sliders are also used to provide quick information and links to certain important content of your website, such as products you'd like your website users buy. It backfires though, because a slider blurs the focus and divides it to multiple shallow choices.
Brad frost calls carousels organizational crutches. They exist because everyone wants their "important" content on the front page and nobody's content can be more important than the other content. Also I have talked with clients who want sliders to add more visuality and (they don't use that word necessarily) flashiness to their site. Sliders are usually added to a website by a designer or requested by owner who wishes to to make the site appear more dynamic. Sliders are glitter of websites. Glitter doesn't add any value to a site and in this case, due to all the reasons listed above, it can reduce the value of the site.
Unless you have a really good reason for using a slider on your site, I have a simple suggestion: Don't use sliders on your website.