Filtering & Escaping Use r In put Validation ctype_alpha() ctype_digit() ctype_alnum() ctype_lower() ctype_upper() preg_match() a ma e s, i t's (y nt ra) Tainted Data Alphabetical Numerical Alphanumeric Lowercase Uppercase E-Mail Addresses Phone Numbers Credit Cards Zip Codes HTML Control Characters Slashes strip_tags() preg_replace() str_replace() stripslashes() urldecode() rawurlencode()