This program is an Internet suite containing all you need to surf the web in a single package. First of all, it has a Web browser, which is not very different from any other, except maybe MS Internet Explorer, which is heavier and slower than most of the other browsers. The SeaMonkey suite also has an e-mail and newsgroups client which can be used insead of MS Outlook or any other client. It is also lighter and faster than its MS counterpart. The suite also has a IRC chat client. All these features are readily available from the program's main interface. You only need to click on the corresponding icon at the left bottom of the interface. You can customize the program by adding themes and add-ons. Since it is based on the Mozilla architecture, its customization features are pretty much the same as those of Firefox.
Although the program is pretty decent, it has several disadvantages too. The main of those is that, to open a new tab or close an existing one, you need to right-click on the tabs bar, open a popup menu and then select the corresponding option. This is awkward and time-consuming. If you want an alternative to your existing web browser, then you may want to try this one.