There are many fantastic points and examples in this essay by Phillip Hoyt. One of the most unique items he brings up is the file type's abilities with regards to Gamma Correction.
"From the LibPNG site: "Gamma correction basically refers to the ability to correct for differences in how computers (and especially computer monitors) interpret color values." There are two factors here: the ability to predict what an image, say a photograph, will look like on another monitor; and the ability to match the colours from different sources on a single page.
"HTML5 (also sometimes referred to as Web Applications 1.0) is a technology developed by the WHATWG, an open community started by three of the four major browser vendors: Mozilla, Opera, and Apple. HTML5 is not so much a replacement for HTML 4.01 or XHTML 1.0 as it is an upgrade or evolution. It aims for backwards compatibility, tries to remove undefined behavior in HTML 4.01 by defining it, and looks at the various browsers’ tag-soup parsing behavior to try to define the best solution that doesn’t break the web. At the same time, it adds sorely
"Microsoft first implemented the XMLHttpRequest object in Internet Explorer 5 for Windows as an ActiveX object. Engineers on the Mozilla project implemented a compatible native version for Mozilla 1.0 (and Netscape 7). Apple has done the same starting with Safari 1.2.
Similar functionality is covered in a proposed W3C standard, Document Object Model (DOM) Level 3 Load and Save Specification. In the meantime, growing support for the XMLHttpRequest object means that is has become a de facto standard that will likely be supported even after the W3C
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