quotations for tag attributes

[htmlnewbie23]

This is a dumb beginner question but as I begin to learn how to write html, I've looked at some examples of existing webpages and have a question about tag attributes.On some pages tag attributes are entered in quotes, in others not so and in some it is a mixture, yet they all seem to display correctly and the same in my browser. For instance, I've seen:<hr size="5" noshade="noshade" width="10%"><hr size=5 noshade="noshade" width=10%><hr size="5" noshade=noshade width="10%">etc.When is inserting " " around an attribute necessary or required and when can they be skipped, if at all?Is the answer I will receive true for all tag attributes or specific to the <hr> tag.I do realize that these attributes are being downgraded in favor of styles, but I would still like to understand the quotations system.

[justsomeguy]

For the sake of consistency, as well as the requirements of more recent specs, it is best to always quote all attribute values.

[pulpfiction]

Its not necessary to use double quotes for values of attributes in HTML but if you want to some XHTML standard then you need to have quotes for values...HTML: http://en.wikipedia.org/wiki/HTML [section 4.3]XHTML: http://en.wikipedia.org/wiki/Xhtml [section 1.2]

[htmlnewbie23]

Its not necessary to use double quotes for values of attributes in HTML but if you want to some XHTML standard then you need to have quotes for values...HTML: http://en.wikipedia.org/wiki/HTML [section 4.3]XHTML: http://en.wikipedia.org/wiki/Xhtml [section 1.2]

Thank you both. That is what I guessed, but I wanted to find out before going too far astray.