Sanitize and validate user input in WordPress the right way
Learn which WordPress sanitisation and escaping function to use for each data type to prevent XSS and SQL injection.
Remove the type Attribute from Script and Style Tags in WordPress
When you run a WordPress site through the W3C validator, you will likely see multiple warnings about the type attribute on <script> and <style> tags. In HTML5, and are redundant — the browser already assumes those MIME types by default. WordPress adds them anyway for backwards compatibility.