Host variable

Hi friends

I am babi. New to this forum.
What is the difference between host variable and bind variable?
What is difference between & and :?

Regards
Babi

&variable_name; (substitution variable)
:variable_name; (bind variable)

For example in a query such as:

OPEN CURSOR (&my_var)
OPEN CURSOR (:my_var)

Sorry I don’t know the exact difference between Bind and Host variable,
Usually we will use Bind variables in SQL and PL/SQL at application level, I think we can use this Host variables at Database level.
I am not so sure about this Please Ignore it...

For details of host,bind varible follow this links [URL="http://download.oracle.com/docs/cd/B10500_01/appdev.920/a97269/pc_04dat.htm#27300"]1 [/URL]& [URL="http://www.akadia.com/services/ora_bind_variables.html"]2[/URL]