HTML minification strips comments, collapses runs of whitespace between tags and removes indentation, typically cutting 10-25% from a page's markup. Because HTML is the very first resource the browser downloads, a smaller document means the parser reaches your CSS and script tags sooner, which shows up in Time to First Byte and First Contentful Paint measurements. The tricky part is that whitespace between inline elements is meaningful — remove it and 'Hello <b>world</b>' can become 'Helloworld' — so this minifier collapses whitespace rather than deleting it entirely, and leaves the contents of <pre>, <textarea> and <script> blocks alone.
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