Test your knowledge: HTML Forms

Review

1. How is a label connected to its control?

   The for attribute must match the control's id. That pairing gives the control its accessible name, powers voice input, and makes the whole label clickable, which matters enormously on touch screens.
2. Why is placeholder text not a substitute for a label?

   A placeholder vanishes on the first keystroke, is commonly rendered in low-contrast gray, and disappears in password manager and autofill interfaces. It suits example values, never field names.
3. What do radio buttons in one question need that checkboxes in one option list do not?

   Radios are one question with shared name and one answer, so a fieldset and legend give the group its name, announced with each option. Checkboxes are independent statements that each carry their own label.
4. Which control is the honest choice for a card number field on mobile?

   type=number adds steppers that make no sense, drops leading zeros, and fights pasting. A text input with inputmode=numeric gives phones the right keyboard while treating the value as the string of digits it really is.
5. A form has required and pattern on every field. What still has to happen on the server?

   Client-side attributes make the browser helpful, but anyone can send any request. The server must validate everything itself, treating the browser's work as convenience for honest readers, never as security.