An idea for writing this blog post inspired me for implementing this feature on two Magento 1 projects, on first project it was one of many changes that were part of A/B testing, on the second one it was part of creating a new visual identity for clients store.
So, what basically is sticky sidebar and why should it be used to improve your conversion rate? Well, just like sticky header, the purpose of sticky sidebar is to have the sidebar element displayed in the viewport at all times (or an at least, when some conditions are met). This is ideal place to move the product options (configurable dropdowns, image swatches etc), add to cart button or any other element that is important for your product. With this being said, your customer is free to browse all of the content on your product and once the decision has been made to purchase the product, the add to cart button is just waiting to be clicked on!
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