AsciiDoc is the language.
Asciidoctor is the processor.
Asciidoctor reads the AsciiDoc source, as shown in the panel on the left in the image below, and converts it to publishable formats, such as HTML 5, as shown rendered in the panel on the right.
Asciidoctor provides built-in converters for three output formats by default: HTML 5, DocBook 5, and man page (short for manual page).
Additional converters, such as PDF and EPUB 3, are provided by separate gems.
Asciidoctor also provides an out-of-the-box HTML experience complete with a default stylesheet and built-in integrations like Font Awesome (for icons), highlight.js, Rouge, and Pygments (for source highlighting), and MathJax (for STEM processing).