Logic and Connection

Hi Every one

I am asking Stupid question I know but pls give me the answer.

There r three Logic
a. Application logic
b. Business Logic
c. Data logic

Can some one pls tell me in detail what this logic do and whats the use of this Logic.

Another question is how to make application fast i.e in Multi user when to open connection and when to close the connection.

Bye
Sajid

There should be something on this in one of these sites :
http://google.yahoo.com/bin/query?p=...c%22&hc=0&hs=0

Especially the :

Quote:

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Overview of Two- and Three-Tier Architectures
... Three-tier thin-client applications are those that have some application logic (business
rules or data access logic) running on the server in a tier that is ...
http://cdc.state.ky.us/dcs/tiers.htm

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One on the first page.