Mustache

There are no if statements and no loops — only sections: {{#items}}...{{/items}} repeats when the value is a list and renders when it is truthy, {{^items}} renders when it is false or empty. All logic therefore has to live in the data you pass in, which is both the entire point and the most common frustration. The compensation is portability: the same template renders identically across forty-plus languages, tested against a shared specification suite, so one template can serve both server and client. {{name}} escapes HTML, {{{name}}} does not. Handlebars is the popular extension that put helpers and conditionals back in.