Link

link_to

method, remote, data, attribute

<%= link_to 'Google', 'http://google.com.sg' %>
<%= link_to 'Top', {controller: :hello, action: :index}, id: :link, class :menu %>

<%= link_to 'Delete' book_path(1), method: :delete, data: { confirm: "Are you sure?" } %>

<%= link_to book_path(@book) do
   imgage_tag "http://xxx.com/book/#{@book.id}.jpg"
end %>

link_to_if, link_to_unless

<% @user = User.new %>
<%= link_to_if @user.nil?, 'Sign in', controller: :login, action: :index %>
<%= link_to_unless @user.nil?, 'Sign in', controller: :login, action: :index %>

link_to_unless_current

If dst of link is current page, output only text
If not, outputs link

<%= link_to_unless_current 'List', action: :current %> |
<%= link_to_unless_current 'Detail', action: :detail %>

mail_to

<%= mail_to 'atmarkplant@gmail.com' %>
<%= mail_to 'atmarkplant@gmail.com', 'Mail' %>