form_tag('/posts')
# => 


form_tag('/posts/1', method: :put)
# =>  ...  ...

form_tag('/upload', multipart: true)
# => 

<%= form_tag('/posts') do -%>
  
<%= submit_tag 'Save' %>
<% end -%>
# => 


<%= form_tag('/posts', remote: true) %>
# => 


form_tag('http://far.away.com/form', authenticity_token: false)
# form without authenticity token

form_tag('http://far.away.com/form', authenticity_token: "cf50faa3fe97702ca1ae")
# form with custom authenticity token