There are a vast number of important considerations when selecting a Web host. Though the hosting services you might be considering will insist emphatically that they are the perfect fit for your company, your first decision should be what kind of service is required to meet your hosting needs. The basic choice falls between three main categories: "shared" hosting, virtual private servers and dedicated servers.

By far the most common choice for a website is "shared" hosting: your website is stored alongside hundreds of other unrelated sites on a single server machine. Sharing the server hosting costs with other clients of the Web host makes this an inexpensive way to host low-value websites. But by its nature, sharing resources can cause problems: when another site receives a huge traffic spike, e.g. caused by the "slashdot effect", your site can become inaccessible. Similarly, to protect its other clients, the Web host may take your website offline if a dramatic increase in traffic flows to your site. In either case, your website becomes unavailable, disastrous if you are running an e-commerce site.

Of course, sudden traffic spikes aren't the only danger which could bring your site to its knees. A client who accidentally over-utilises the processing capabilities of the machine or causes run-away memory usage can cause downtime. Further, in order to maintain the server software by applying updates and security patches, the machine may have to be rebooted regularly, causing downtime even if your site does not actually benefit from those changes. Generally, the more clients sharing a machine, the more downtime becomes likely.

Another disadvantage with shared hosting is a lack of flexibility: the Web server software will be configured as your Web host sees fit. This might not cover all your requirements and may fall short in terms of features, performance or reliability. Since the server is shared by other clients, Web hosts are typically reluctant to alter any configuration on a one-off basis.

The alternative to shared hosting is to obtain your own server. These come in two forms: virtual private servers or dedicated server hosting. With the latter, you have a complete machine at your disposal. You can configure it how you need, never have to worry about other clients unfairly consuming resources and bringing your site down, and you can control what and when you update software to minimise impact on your operations. Whilst relatively expensive, dedicated server hosting gives you unmatched reliability and flexibility, exceeding 99.99% annual uptime with an enterprise-grade host.

If the cost of a dedicated server solution is prohibitive, you can consider virtual (private) servers, also known as virtual dedicated servers. You receive your own server environment, complete with operating system, limited but guaranteed memory, hard disk space and processor time, all on shared hardware. Hence you share the hardware costs whilst being able to create totally custom environments: use only the software you need, run security updates only when appropriate for your circumstances, and feel safe in the knowledge that your resources are guaranteed and data is isolated from other clients. With a reputable Web host, a typical server machine can host anywhere from 4 to 32 virtual servers. Naturally, the disadvantage is that you are sharing hardware: disk access can be slower than in a dedicated server, and if a sudden burst of traffic was received by another client's virtual server, yours could still become unresponsive. The Web host may shut down the offending virtual server to protect the interests of its other clients.

Assessing the type of hosting you use is important: weigh up the benefits and costs of each approach, and talk to your Web host to agree upon the best strategy for your business.