Marko is a high performance UI library from eBay. Marko began life as a templating language, so let's begin there.
Most templating languages are pretty simplistic, they understand their own constructs, but don't understand the HTML structure itself. Marko is different. Marko fully understands the HTML language, in fact, the first version of Marko was built on top of an off-the-shelf HTML parser. We've since developed our own parser that extends the language by adding typed attributes, argument expressions and even a concise syntax. It's quite beautiful.
<h2>Hello ${data.name}!</h2>