Can we use "&" in a url ? or should "and" be used?
Unless you're appending variables to the query string, encode it.
encode '&' with &
(this answer is based on your use of tags)
If you are asking what to use "&" or "and" when registering the name of your URL, I would use "and".
EDIT: As mentioned in comments "& is an HTML character entity and not a URI character entity. By putting that into a URI you still have the ampersand character and additional extraneous characters." I started answering before fully understanding your question.
An URL is generally in the form
scheme://host/some/path/to/file?query1=value&query2=value
So it is not advisable to use it in an URL unless you want to use it for parameters. Otherwise you should percent escape it using %26, e.g.
http://www.example.com/hello%26world
This results in the path being submitted as hello&world. There are other characters which must be escaped when used out of context in an URL. See here for a list.
Yes, you can use it plain in your URL path like this:
http://example.com/Alice&Bob
Only if you want to use it in the query you need to encode it with %26
:
http://example.com/?arg=Alice%26Bob
Otherwise it would be interpreted as argument separator when interpreted as application/x-www-form-urlencoded.
See RFC 3986 for more details.