What is a attribute

Answer 1

attributes are the limitations of the tag
for example
a body tag which background color is red
then bgcolor is a attribute not red
red is value of attribute

Answer 2

HTML5 Attributes

HTML5 added the following attributes for <input>:

autocomplete
autofocus
form
formaction
formenctype
formmethod
formnovalidate
formtarget
height and width
list
min and max
multiple
pattern (regexp)
placeholder
required
step

and the following attributes for <form>:

autocomplete
novalidate

From http://www.w3schools.com/htmL/html_form_attributes.asp