You may have multiple domain names and ‘point’ them all to your web site, so users can access your web site with any of the chosen names.
For many companies it is a good idea to register other secondary top level domain names such as ‘.net’ or ‘.org’ to protect your business brand. Very few people will use these domain names to access your website, but by registering them you prevent other businesses taking them to steal web site visitors or damaging your brand by displaying obscenities at their addresses.
If your domain name combines two separate words, make sure you register versions with and without hyphens. Search engines prefer domain names with hyphens and users prefer them without. If it is easy to misspell the domain name – consider registering the misspelt version of the domain name.
It is also a good idea to register the domain name of individual products, especially if these are well known brands and people have heard of them and are searching for them. This will also protect your product names.