A form control has the focus when it's selected and ready to receive input. For example a text box will contain a blinking cursor when it has the focus. After you type your input into the text box and press the keyboard [Tab] key, the focus moves to the next control in the tab order. By pressing the tab key, users can move the focus through the controls in your form.
The default tab order is the order in which the controls appear in the html code. You may prefer to set the tab order yourself. To set the tab order give each form element a tabindex attribute and set their number values to the order you want the tabs to work.
In the form shown below, the controls appear in the code in the same order they appear on the page; top to bottom. But because the tabindex of the Email Address text box is lower than the tabindex of the Comments textarea box, the focus goes to the Email Address text box first.
To set the initial focus, you'll need to use a bit of Java Script (at least until all browsers catch up with HTML5. The easiest way to do this is to use the getElementById method in the webpage's onload event. An example is shown below.
Also note that the browser window controls also involved in the tab order.
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