render is one of the often used view helpers, we use it to extract sub part view. We can pass object, collection or local variables to the partial views. From rails 2.3, more simplified syntax for render are provided that makes render helper cleaner. Here I will show you the contrast.

Render simple partial

Before

<%= render :partial => 'sidebar' %>
<%= render :partial => 'shared/sidebar' %>

After

<%= render 'sidebar' %>
<%= render 'shared/sidebar' %>

Render partial with object

Before

<%= render :partial => 'posts/post', :object => @post %>

After

<%= render @post %>

Render partial with collection

Before

<%= render :partial => 'post', :collection => @posts %>

After

<%= render @posts %>

Render partial with local variables

Before

<%= render :partial => 'comments/comment', :locals => { :parent => post } %>

After

<%= render 'comments/comment', :parent => post %>