1.20 HTML Forms

HTML Forms are used to select different kinds of user input.

HTML Forms

HTML forms are used to pass data to a server.

An HTML form can contain input elements like text fields, checkboxes, radio-buttons, submit buttons and more. A form can also contain select lists, textarea, fieldset, legend, and label elements.

The <form> tag is used to create an HTML form:
<form>
.
input elements
.
</form>

HTML Forms - The Input Element

The most important form element is the <input> element.

The <input> element is used to select user information.

An <input> element can vary in many ways, depending on the type attribute. An <input> element can be of type text field, checkbox, password, radio button, submit button, and more.

The most common input types are described below.

Text Fields

<input type="text"> defines a one-line input field that a user can enter text into:
<form>
First name: <input type="text" name="firstname"><br>
Last name: <input type="text" name="lastname">
</form>

How the HTML code above looks in a browser:

First name: 
Last name: 

Note: The form itself is not visible. Also note that the default width of a text field is 20 characters. 

Password Field

<input type="password"> defines a password field:
<form>
Password: <input type="password" name="pwd">
</form> 

How the HTML code above looks in a browser:

Password: 

Note: The characters in a password field are masked (shown as asterisks or circles).

Radio Buttons

<input type="radio"> defines a radio button. Radio buttons let a user select ONLY ONE of a limited number of choices:

<form>
<input type="radio" name="sex" value="male">Male<br>
<input type="radio" name="sex" value="female">Female
</form>

How the HTML code above looks in a browser:

Male
Female

Checkboxes

<input type="checkbox"> defines a checkbox. Checkboxes let a user select ZERO or MORE options of a limited number of choices.

<form>
<input type="checkbox" name="vehicle" value="Bike">I have a bike<br>
<input type="checkbox" name="vehicle" value="Car">I have a car
</form>

How the HTML code above looks in a browser:

I have a bike
I have a car

Submit Button

<input type="submit"> defines a submit button.
A submit button is used to send form data to a server. The data is sent to the page specified in the form's action attribute. The file defined in the action attribute usually does something with the received input:

<form name="input" action="html_form_action.asp" method="get">
Username: <input type="text" name="user">
<input type="submit" value="Submit">
</form>

How the HTML code above looks in a browser:

Username: 

If you type some characters in the text field above, and click the "Submit" button, the browser will send your input to a page called "html_form_action.asp". The page will show you the received input

Tag                                                                      Description

<form>                                                       Defines an HTML form for user input
<input>                                                       Defines an input control
<textarea>                                                  Defines a multiline input control (text area)
<label>                                                       Defines a label for an <input> element
<fieldset>                                                   Groups related elements in a form
<legend>                                                    Defines a caption for a <fieldset> element
<select>                                                      Defines a drop-down list
<optgroup>                                                 Defines a group of related options in a drop-down list
<option>                                                     Defines an option in a drop-down list
<button>                                                     Defines a clickable button
<datalist>                                                    Specifies a list of pre-defined options for input controls
<keygen>                                                    Defines a key-pair generator field (for forms)
<output>                                                      Defines the result of a calculation