A typical Rails CRUD app will have an index. The index will list a collection of resources, like blog posts. In our index.html.erb view, we might do this:

<% @posts.each do |post| %>
  <%= post.title %>
<% end %>

This will list out the titles for each of our blog posts. However, there is a more elegant way which leverages Rails’ defaults. If we instead do this:

<%= render @posts %>

Rails will look for a partial in the app/views/posts directory with a name equal to the model name. If the model name is Post, Rails would look for a file named _post.html.erb. We might write it like this:

<%= post.title %>

By default, Rails provides us with a local variable with the same name as the partial. For more information, check out the documentation.