Question: Can anyone give me an Idea about how to manage preferences of every user in asp.net?
for example I have a couple of parameters for all my users and they are correspondingly related to the user 
For instance his birthday or the his salary and I need these specific parameter frequently I did save them in my database and I dont want to fetch them each time I need them
Many thanks

Answer: 
Normally these would be fetched once and stored in the session state. A few warnings:

1) be careful on how much you store in the session. Must be up to a few KB for each user

2) With a server farm, you have to use a sticky session or store the session in SQL or state server

3) Beware of session hijack and make sure important stuff are not stored

4) Nowadays, going to database to get a few records is cheap, do not knock it automatically!
My answer would be to not worry about how you store the information you need at first but worry about what information you need and how you plan to use it. Create a user information object and use it in your code. When you are ready to test plug you user object upto a data store. They type of information you want is most generally stored in a database but that is not a hard and fast rule.