Really? My recollection is that Gmail was substantially different in the extent to which it was an in-browser Javascript app built around server-side data requests. That's in contrast to something where applications were a series of mostly-static pages.

At the time this change was known as AJAX, and GMail is listed as a pioneer: https://en.wikipedia.org/wiki/Ajax_(programming)

Squirrelmail, by contrast, rendered a new page for most user actions. Especially the viewing of messages.

> Gmail wasn't much different from the status quo

GMail was different because it offered an outlandish 1GB of mail space, when everywhere else you got 1-10MB mailboxes. Since it was launched on April 1st, most people did not believe it at first. And (at the time) huge space allowed users to keep and search all old email, instead of deleting old emails being a weekly chore.

Pine

I remember how impressed I was when Google Maps was released. Instead of having to click on arrows to reload the page with a new map, you could just drag and it would automatically load new map tiles!

Google Earth (the native application) is really old and abandoned by now, but its still better than the new "web" version that only works in Chrome.

Gmail was first massively used single page web application. Somewhat ironically it was built on top of technology meant for Outlook Web Access (ie. XMLHttpRequest as ActiveX component in IE and as an DOM extension in Gecko). AJAX is name that was conceived to describe that approach to webapps, with the somewhat funny fact, that google at the time described it as javascript (from time to time with the addendum: "done right")