erb

ERB, short for Embedded Ruby, is a templating system that is part of the Ruby programming language. It allows Ruby code to be embedded directly into text documents, most commonly HTML, to generate dynamic content. When rendered, the template is converted into Ruby code and evaluated within a given binding, producing a final string.

Syntactically, ERB uses tag delimiters to distinguish code from text. The most common are <% ... %> for Ruby code that is executed without producing direct output, and <%= ... %> for expressions whose results are inserted into the template. Whitespace and trimming can be controlled with variants like <%-, -%>, which remove surrounding whitespace.

ERB files typically have the .erb extension and are used in Ruby applications and frameworks such as Ruby on Rails. To render a template in Ruby, you require 'erb', read the template text, create an ERB object with ERB.new(template), and call result(binding) to produce the output. The template can access variables and methods available in the binding at render time.

Security and escaping considerations apply when rendering HTML. ERB itself does not automatically escape HTML special characters; frameworks often provide escaping helpers or use additional layers to mitigate cross-site scripting. ERB remains a foundational tool for Ruby-based templates, with alternative templating engines like Haml and Slim available if different syntax or features are desired.