"<%= %>", "<%- %>" and "<% -%>"

Duke Yamamoto wrote:

When I want to show output,
"<%= %>"
When I do not want to show output,
"<%- %>" or "<% %>"
What about this?
"<% -%>"
Is this same as "<%- %>"?

<%# %> or <%# -%>
For commenting out ERB code.