HTML Forms

Forms are used to collect data input by a user. They can be used as an interface for a web application for example or to send data across the web.
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>
Input elements:
Text fields:
<form>
<input type=”text” name=”firstname” /> : First Name <br />
<input type=”” name==”lastname” />: Last Name
Note: the form itself is not visible. Also note that the default width of a text field is 20 characters.
Password field:
<form>
<input type=”password” name=”pwd” />: 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

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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

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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.