Input Type Checkbox

hi every one
i am new in computer field and i come across term Input Type Checkbox. how this works ?why it is much important and how i can use it better ? please kindle provide me answers of my question thank you

The checkbox input type creates boxes that can either be checked or unchecked by the user. You specify what the boxes will send you if checked. These can all be checked at the same time. CHECKBOX is a TYPE attribute value to the INPUT element for FORMs. It indicates a form field used for a boolean choice, or for attributes that can take multiple values at the same time. The default state for a checkbox is OFF. Only checkboxes that are in a checked state should be submitted to the form processing script.

<input type="checkbox" /> Description:The <input type="checkbox" /> tag adds checkboxes to forms.

<input type="checkbox" /> Web Browser Support:

• Netscape 2, 3, 4, 6, 7
• Mozilla 1
• Firefox 1
• Internet Explorer 2, 3, 4, 5, 6
• Opera 3, 4, 5, 6, 7, 8

Common Attributes
%Core%
[2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6B1|O4]
%Accessibility%
[2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6|O5]
%Events%
[2|3|3.2|4] [X1|X1.1] [IE3|M|N2|O3]
%Language%
[2|3|3.2|4] [X1|X1.1] [IE4|M|N|O]
%Data%
[2|3|3.2|4] [X1|X1.1] [IE4|M|N|O]
%Editing%
[2|3|3.2|4] [X1|X1.1] [IE5.5|M|N|O]

Specific Attributes
Accesskey
[2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6B2|O7]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? No
Description:
This is a method of giving access/focus to an active HTML element using a keyboard character. This is a common GUI paradigm also known as a "keyboard shortcut" or "keyboard accelerator" A single character is used as the value of this attribute. In addition, a platform-dependent key is usually used in combination with the ACCESSKEY character to access the functionality of the active field.
Values:
A single, case-insensitive alphanumeric character from a browser's character set.
Align
[2|3|3.2|4] [X1|X1.1] [IE|M|N6B1|O]
Standards Details: Deprecated in HTML 4.x/XHTML 1.0. Dropped in XHTML 1.1 in favor of CSS.
Required? No
Description:
This attribute specifies the alignment of text following the INPUT reference relative to the field on screen. LEFT and RIGHT specify floating horizontal alignment of the form field in the browser window, and subsequent text will wrap around the form field. The other options specify vertical alignment of text relative to the form field on the same line.
Values:
Left | Right | Top | Texttop | Middle | Absmiddle | Baseline | Bottom | Absbottom
Checked
[2|3|3.2|4] [X1|X1.1] [IE1|M2A1|N1|O2.1]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? No
Description:
This is an optional stand alone attribute which turns the checkbox on if present. If this attribute is omitted, the initial state is off.
Values: Stand-alone or ON | OFF [DEFAULT]
Disabled
[2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6B1|O5]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? No
Description:
This is a stand-alone attribute which indicates the element is initially non-functional. Disabled form elements should not be submitted to the form processing script.
Values: NA
Name
[2|3|3.2|4] [X1|X1.1] [IE1|M2A1|N1|O2.1]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? Yes
Description:
This is a required attribute that associates a symbolic name to the field for submittal to the form processing script.
Values: Alphanumeric characters.
Readonly
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O5-5.x]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? No
Description:
This is a stand-alone attribute which tells the browser that content in the field may not be modified by the reader.
Values: NA
SDAPref
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]
Standards Details: NA
Required? No
Description:
This is an SGML Document Access (SDA) attribute. SDA attributes are designed to transform HTML (and other SGML-based documents) to the ICADD DTD - which is used in creating accessible documents for users with visual disabilities (rendering in Braille, large print, speech synthesis, etc.) The attribute value specifies content to be added BEFORE the original element content (in this case the string "Input: ") when the SDA document is rendered.
Value: "Input: "
Tabindex
[2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6B3|O7]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? No
Description:
"Tabbing" is a method of giving access/focus to an active HTML element using a standard keyboard sequence. All the active elements in a document can be cycled through using this sequence (ex: Windows TAB key.) The order of the active elements in this cycle is usually the order they occur in the document, but the TABINDEX attribute allows a different order to be established. The use of this attribute should create the following tabbing order cycle if the browser supports the attribute:

1. Active elements using the TABINDEX attribute with positive integers are navigated first. Low values are navigated first.
2. Active elements not specifying any TABINDEX attribute

Those elements carrying a DISABLED attribute or using negative TABINDEX values do not participate in the tabbing cycle.
Values: Positive or negative integers.
Type
[2|3|3.2|4] [X1|X1.1] [IE1|M2A1|N1|O2.1]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? Yes*
Description:
* This is the required TYPE attribute for this INPUT mechanism. From the strict view, the TYPE attribute is not required.
Values: CHECKBOX
Value
[2|3|3.2|4] [X1|X1.1] [IE1|M2A1|N1|O2.1]
Standards Details: In all HTML 4.x/XHTML DTDs
Required? Yes
Description:
This is a required attribute representing the symbolic result of the checkbox field when activated that is passed to the form processing script.
Values: Alphanumeric characters.

When a INPUT type=checkbox element is selected, a name/value pair is submitted with the FORM. The default value of INPUT type=checkbox is on.

The height and width styles are exposed to the INPUT type=checkbox element as of Microsoft® Internet Explorer 5. The size of the element is set based on the values provided by the author, except when a given size is below a particular minimum. The size is calculated as follows:

* If the height or width is greater than 20 pixels, the padding around the check box is set to 4 pixels, and the inner height or width is set to 8 pixels.
* If the height or width is less than 20 pixels but greater than 13 pixels, the padding around the check box is equal to one half the specified height or width minus 13. For example, if the specified width of the check box is 17, the equation would be: (17-13)/2.
* If the height or width is less than 12 pixels, the padding around the check box is set to 0 and the inner width is set to the value specified by the author.

The INPUT type=checkbox element is an inline element and does not require a closing tag.

This element is available in HTML and script as of Microsoft® Internet Explorer 3.0.