Buying server hardware -- the racks or blades and power supply and cooling systems that go along with them -- is a big step toward taking control of your company's information flow. But what really makes a server tick is the software inside.Like an operating system in an ordinary desktop computer, server software give your servers a purpose and means to do their jobs. Unlike operating system software, server software often has just one, specific job to do: dish up Web site pages, handle faxes or e-mail, allow the interchange of corporate files, manage customer data and so on.Practically speaking, you'll need a dedicated server for each, and server software to match. Covered in this guide:1. Understanding the different purposes of server software2. Selecting email server software and fax server software3. Web server software choices4. File transfer protocol server software A server and server software for every purpose Once upon a time, server software was relatively simple stuff. Now, though, most complex business processes require a server, and the right server software, for each. Accounting, customer relationship management, e-mail, Web sites, e-commerce -- nearly any business task could be done with its own variety of server software. For email, server software choices are many Email server software has been a principal focus of server software developers for many years, so the choices here are broader and cheaper, in general. Similarly, you can configure server software to deal with faxes, known as fax server software. File transfer protocol, or FTP server software gives you security We all love e-mail, but there is pretty much nothing secure about it. If you need to regularly send confidential data, contracts, customer information or other sensitive documents, FTP server software is the solution. For e-commerce, you'll need Web server software Many small businesses are moving their Web sites to managed hosting in order to avoid running their own server software for Web site needs. Your traffic, though, may be high enough or important enough to your model to justify the expense. The war of late has been between "open source" server software and its primary competitor, Microsoft Windows. Open source is often cheaper, but could take more resources to manage. Price both carefully over several years, or bring in consulting help before making a big commitment. Similarly, there has been a lot of pressure on email systems. Generally, unless you need for regulatory reasons to recall every single email in your system, managed email -- which means the server software is offsite -- can be a blessing. Shop carefully. Not sure what's the right fit? Mix and match. Since most server software requires its own software to run correctly, you could easily buy server software for accounting but outsource your e-mail or Web site to a managed hosting provider.