Registering a few extra domain names is a simple way to protect your brand online. It stops someone else from using a name that customers could confuse with yours, and it catches visitors who type a variation of your address.
For example, if your business is bookshop.com, you might also register bookshop.net, book-shop.com or the country extension your customers use. Think about the singular and plural forms and a hyphenated version. There is no need to buy every extension; the ones your customers are likely to type are enough.
Extra domains can be pointed at your main website, so everyone ends up in the same place.