Input validation

Strip all tags for email field

$email = sanitize_email( 'info@info.si' );

Email verification

$valid_email = is_email( 'info@info.si' );

Strip all tags

$value = wp_strip_all_tags( 'text to strip' );

Sanitize string from input

$string_input = sanitize_text_field( 'text to sanitize' );

Sanitize multi-line string from input

$textarea_input = sanitize_textarea_field( 'multi-line text to sanitize' );

Create nonce

wp_nonce_field( 'agiledrop_action', 'agiledrop_nonce_field' );

Verify nonce

wp_verify_nonce( $_POST['agiledrop_nonce_field'], 'agiledrop_action' );