Popular products in large online stores frequently sell out. However, how they communicate this to a customer on their website may have an impact on their search engine optimisation (SEO), sales and customer experience, and, ultimately, conversion. Most online stores leave out-of-stock products unpublished or unaltered on the product description

You don't have to lose customers just because a product is sold out or out of stock. Rather, it is a chance to engage shoppers and convert them into customers - even when they're unable to purchase the exact item that led them to your store.