title: Make text input fields remember previously entered data
body: <p>My text inputs seem not to remember values that have been typed before. For example, many websites that I don't even have an account on, but have, for example entered my email address before (buying a train ticket as a "guest") give me a sort of dropdown with email addresses I've used in the past. Yet my form does not do this. It obliges me to type it out completely every time. It seems to be the opposite of <a href="https://stackoverflow.com/questions/13607378/input-text-without-previously-entered-value">this question</a>...</p>
  
  <p>I have simple inputs like <code>&lt;input type="text" id="firstName" placeholder="First name" /&gt;</code></p>
  
  <p>And they are submitted with simple a jQuery Ajax post. Something like <a href="http://jsbin.com/utepax/2/edit" rel="noreferrer">this</a>. However the Ajax isn't working on jsbin on that example, I just show it to demonstrate my basic structure. Is there a jQuery plugin for this? Is there a way I can control this seemingly browser-driven behavior?</p>