Difference between “<%=” and “<%” when mixing ruby with html?

Question

I\'m learning Rails, and i\'m doing a exercise which i have to mix some html with ruby in a view file.

What is the main difference between \" <%= #code %> \" and \" &

Answer 1

<%= something which you would like to have displayed in your view %>
<% something you would like to have hidden, 
(or something which doesn't display anything in the view) such as a
 conditional statement %>

<% if @post.nil? %>
    <%= render "nilNotify" %>
<% else %>
    <%= @post.content %>
<% end %>

Answer 2

<%= 1 + 2 %> will evaluate AND display the result. In this case, you should see 3 in your view.

<% 1 + 2 %> will evaluate but will not display the result in the view. In this case, you will not see 3 in your view.