Google showed the world that web e-mail could be as robust and functional - if not more so - than a regular e-mail client when they released the beta version of Gmail in 2004 to the general public.
The Google Approach to Mail
Gmail has changed the face not only of web email but of web applications in general. When Gmail was first shown in 2004 to a substantial audience of beta testers, it was quite different from what consumers had been conditioned to expect from a web application. It was the first time in history that an online email system didn't require full page reloads every time that you clicked on a new page. You could easily sort and search your mail. Storage was virtually unlimited for most users - and all for free. It's no wonder why Gmail has grown to become one of the most popular webmail applications.
Who Invented it?
The program began as a pet development project of Paul Buchheit primarily for people already working at Google, but it rapidly showed its promise. It was opened up to 1,000 users in March of 2004 to much fanfare and speculation among the technology press, and more users were soon invited in through the Google-owned Blogger service and through a number of other avenues. To cut down on spam in the early days, Google used viral marketing by making it so that new users could only be invited by existing ones.
The strength of the application along with the illusion of exclusivity brought on by the use of the invitation mechanic all combined to make Gmail one of the most talked about releases in application history. The feature that allowed it to search the contents of an entire email archive using Google's search engine was one of the top draws, as was the easy-to-read "conversation" user interface that grouped together linked emails in a clear and appealing fashion. The highly effective spam filtering also made it an unusually enjoyable client to use.
Past and Present Concerns on User Privacy
One feature, however, that was and remains highly controversial, was the way that Google content spiders examine the content of all emails that enter and exit Gmail accounts and use them to tailor ad content to end users. Some have argued that this is a violation of privacy, but no humans go over the emails that are interpreted by the system. It enables Google to sell ads for higher rates than they would be able to otherwise, as they can give marketers reasonable assurance that the targeted users will at least have a passing interest in their products.
Evolving into a Business Solution
GMail has evolved into a messaging and collaboration business solution as well. In September 2007, Google acquired messaging security hosting company Postini and can now rebrand Gmail products to fit your own domain, including the message hygiene and security benefits from Postini. The Instant Messaging and Calendar features complement Gmail for business. Oddly, though, after more than 4 years, the GMail logo still shows "beta".