<li><strong>To return an error code use <codeclass="python hljs"><spanclass="hljs-string">'abort(<int>)'</span></code> and to redirect use <codeclass="python hljs"><spanclass="hljs-string">'redirect(<url>)'</span></code>.</strong></li>
<li><strong><codeclass="python hljs"><spanclass="hljs-string">'request.args[<str>]'</span></code> returns parameter from the query string (URL part after the ?).</strong></li>
<li><strong><codeclass="python hljs"><spanclass="hljs-string">'request.args[<str>]'</span></code> returns parameter from the query string (URL part after '?').</strong></li>
<li><strong>Use <codeclass="python hljs"><spanclass="hljs-string">'session[key] = value'</span></code> to store session data like username, etc.</strong></li>