embedded ruby(ERb)

include ruby in html file( in the view directory)
ex:
<%= 'This line is displayed in the browser' %≷
displayed in the browser

<% 'This line executes silently, without displaying any output' %≷
not displayed in the browser

template:
3 extensions:
rhtml: for HTML
rxml: for XML
rjs: for JaveScript( Ajax)