Where do you host your website? What are your options? When will you know that you need to upgrade?
Most websites are hosted with web hosting companies like godaddy.com. A typical site is housed on a web server with many other sites. A web server is just an ordinary computer with special software and security set up. The cheaper hosting is cheap because the resources required (ie: gigabytes, bandwidth, software,etc.) are shared with many other sites.
Once your site requires more band width or storage space, dedicated web servers can be purchased. Some web hosting companies also require a dedicated server if you need to install an SSL certificate for additional security. A dedicated server isn't necessarily a server that is physically separate from another server, but may be partitioned separately virtually on the same computer hard drive. Because this requires separate software and software licences, hosting on a dedicated server can be quite expensive.
Another option is hosting on your own hardware. This requires a dedicated computer; not one that you or your staff would normally use. You'll need to make sure you have a good broadband connection and in most cases a dedicated IP address assigned by your internet provider. You'll also need to install the web software necessary and make sure the system is properly running at all times and backed up. The software should be updated when necessary. This option is best when you have IT staff with time on their hands.
Websites can provide marketing, sales, customer interactions, and customer service at reasonable costs. Keep in mind bandwidth needed, storage space for your site to expand, and security requirement as you shop for hosting.