Validating is the process of checking whether user input meets specific requirements—before your website accepts or processes it. If escaping makes data safe, and sanitizing makes it clean, then validating makes sure it’s correct.

Think of it as a bouncer at the door: even if someone is well-behaved (escaped) and clean (sanitized), they still need to meet the dress code to get in. Validation checks that everything looks right before it’s allowed through.

What validation looks like in action

You’ve likely seen validation messages on forms like:

• “Please enter a valid email address”
• “Password must be at least 8 characters”
• “This field cannot be left blank”

That’s validation at work—guiding users to input data that’s formatted correctly, matches the expected type, and fits within limits you’ve defined.

Why validation matters for your business

Even though it sounds technical, validation affects a lot of real-world outcomes:

• Better data quality – No typos, fake emails, or missing fields
• Fewer support issues – Users get real-time guidance, reducing errors
• Increased trust – Clean, guided forms feel professional and reliable
• Stronger security – Prevents unexpected or suspicious inputs from slipping through

In other words: validation keeps your website and your database healthy.

Types of validation

Validation typically happens in two places:

• Client-side (in the browser): Offers immediate feedback to the user. Fast, but not foolproof.
• Server-side (on your web server): The secure backup layer that confirms everything is still valid, even if a user bypassed browser checks.

You need both.

Examples of what can be validated

Your website might validate:

• Email addresses (format and uniqueness)
• Phone numbers (digits only, proper length)
• Password strength (length, symbols, numbers)
• Dropdown selections (must be from allowed options)
• File uploads (type and size restrictions)
• Credit card numbers (format, length, Luhn algorithm)

Without validation, you risk collecting messy, broken, or even dangerous data.

What happens when validation fails?

Ideally, your form or interface provides a clear message—e.g., “Please use only numbers” or “This field is required.” Good validation doesn’t just reject inputs; it helps users correct them.

That’s part of a great user experience—and often, better conversion rates.

Validation in WordPress and CMS platforms

Platforms like WordPress handle validation in both plugins and custom code. Developers use built-in functions and filters to ensure that fields like usernames, settings, or post content meet specific criteria before they’re saved or processed.

In forms (like with Contact Form 7, Gravity Forms, or Fluent Forms), most fields support validation rules like “required,” “email,” “number,” or custom logic.

Bottom line

Validation makes sure that the data your website collects is complete, accurate, and usable. It reduces errors, protects against abuse, and helps create smoother experiences for your visitors. While your users see it as a helpful prompt (“Oops, please fix this”), for your business, it’s one more step toward clean data, security, and professionalism.