You can create as many Web applications as you feel are necessary, but the big thing about creating different Web applications is that you can isolate site collections from each other. And why is isolation a good thing? Well, if each Web application has its own configuration, that means that you can then do the following:

• Use different authentication. Giving each Web application its own authentication scheme means you can have one Web application for internal use and another for external access.
• Use separate application pools. If you set it up so that each Web application uses its own application pool in Internet Information Services, you can keep the applications separate from each other on the server so they can’t corrupt each other.
• Use separate databases. By using different databases for each Web application, you can isolate content for backup and restore operations.

To create a new Web application, follow these steps:

1. Click the Application Management tab in the SharePoint Central Administration site.

2. Click the Create or Extend Web Application link in the SharePoint Web Application Management section. The Create or Extend Web Application page appears. On this page, you have two options: Create a new Web application, or extend an existing one. These steps create a new one.

3. Click the Create a New Web Application link. The Create New Web Application page appears.

4. In the IIS Web Site section, accept the default option to Create a New IIS Web Site. Here’s a list of handy things to know about this option:

• You can select the Use an Existing IIS Web Site option if you’ve already created the Web site with IIS. It’s best to let SharePoint handle the creation of Web sites in IIS.
• The IIS Web Site section includes a default description and path. Accept these defaults unless you have a reason to change them.
• You have the option to set the port that IIS uses to access the site. SharePoint randomly generates a number to use for the port. You may change it if you want. Just make sure the port number doesn’t conflict with any existing port numbers.
• Be sure to set the port to 80 if you’re creating the primary content Web application. Otherwise, your users have to type the port every time they pull up the site in the browser.
• Host headers are a new feature in this version of SharePoint; they allow you to map multiple domain names to a single Web site. Type the domain name you want to map to the Web application in the Host Header field.

5. In the Security Configuration section of the Create New Web Application page, select the default values unless your network administrator gives you different information. In this section, you have the choice to select your authentication provider.

The default option is NTLM (short for Windows NT LAN Manager, an authentication protocol used for Windows NT 4.0 networks). Kerberos is more secure, however, so be sure to check with your network administrator.

If you want your Web application to use Secure Sockets Layer (SSL) for an added layer of protection, you can enable that capability by selecting the Yes radio button for SSL. SSL encrypts data sent to and from the Web application.

6. Type a URL to use as the load-balanced URL. By default, the URL is the servername and port. The load-balanced URL is the domain that’s used in all the links that point to the Web application.

7. In the Application Pool section, accept the default option to create a new application pool. By creating a new application pool, you’re assured that your Web application is isolated from other Web applications on the server. If one crashes, yours won’t crash as well.

You want to enter a username and password for the application pool to use. The username and password that you enter here is the identity used by the application pool. Microsoft recommends that you use a unique domain account for each application pool you create. The application pool account has access to all the content in the Web application. See your network or security administrator for assistance with creating domain accounts.

8. In the Database Name and Authentication section, enter the name for the database server, database, and service account to use for database authentication.

The database server is the name of the server where your database is hosted. I suggest you give a meaningful name to the database itself. Using the same My Site example from Step 7, I append MySite to the database name so I can easily recognize the database.

If you want to use an existing database with your Web application, you need to extend an existing Web application. Refer to Step 2 for more information.

The default option for database authentication is Windows authentication. I suggest you use Windows authentication unless you have a specific need to use SQL authentication. There’s no reason to create a separate set of accounts in SQL Server to manage.

9. In the Search Server section, select a server to use as the search server for this Web application. If you’re using MOSS 2007, search is provided by the Office SharePoint Server Search shared service.

10. Click OK. The Operation in Progress page appears. Wait while the Web application is created. The Application Created page appears after the application is created. The application has no site collections, so a link is provided to create a new site collection.

After you create your Web application, you must create a site collection before you can pull it up in the browser via the URL. You can also see the content database created for the Web application in SQL Server Management Studio and the Web site in IIS Manager.