Html attributes: quoted or unquoted? [duplicate]

Question

For some html attributes, I can use quotes around the values, or not:

For example, I can do

<table colspan='1'></table>

Or

<table colspan=1></table>

Is there any difference between these two ways? Which is the more conventional way of doing things?

Answer 1

Wrap your values in quotes (single or double, just don't mix them):

1. It's necessary for many values ( class="container modal warning" )
2. It prevents confusing values with later attributes ( class="foo"id="bar" )
3. People will like you, and treat you kindly.

During Tokenization, all three are considered (single, double, and none).