The web interface is one of the ways to access Gmail and you can choose from many flavors of web-based Gmail. If the standard web interface doesn't load, it's a good idea to try the more secure SSL interface at https://mail.google.com or the basic HTML mode at http://mail.google.com/mail/h.
Gmail also offers other ways to read your email: you can use POP3 or IMAP in almost any email client for desktop or mobile phones. If you use Windows, you already have Outlook Express or Windows Mail, but you can install a better application like Thunderbird. Before opening a mail client and entering Gmail's settings, it's important to enable POP and IMAP from this page (Gmail settings/ Forwarding and POP, IMAP). POP and IMAP access is disabled by default and it can only be enabled from the web interface.
Gmail's web interface was down for more than 2 hours today. "If you've tried to access your Gmail account today, you are probably aware by now that we're having some problems. Shortly after 9:30am GMT our monitoring systems alerted us that Gmail consumer and businesses accounts worldwide could not get access to their email." The only way to access your mail was using a mail client, but the POP/IMAP access had to be already enabled from Gmail's settings page.
What can we learn from today's outage? It's important to know that there are alternate ways to access Gmail and you should enable POP and IMAP, even if you don't intend to use them regularly.