How link to works

gistfile1.txt

<%= link_to "Text", "/link" %>
    <a href="/link">Text</a>

    <%= link_to "Text", product_path(product) %>
    <a href="/products/1">Text</a>

    <% link_to "<span class='icon'>Text</span>", '/link' %>
    <a href="/products/1">
      <span class='icon'>Text</span>
    </a>

    <%= link_to '/link' do %>
      <span class='icon'>Text</span>
    <% end %>
    <a href="/products/1">
      <span class='icon'>Text</span>
    </a>

    <%
      def link_to(product)

        if product.is_a?(ActiveRecord::Base)
          "/products/1"
          product_path(product)
          "product_path"
          "#{product.class.name.underscore}_path"
        else
          product
        end
        
      end
    %>