how many session we can use in website /web application?

There are no limit of use of session in asp.net. It totally depends upon the application server where the application is host.

Unlimited session can be created in a web application But it depends on server in which application is hosted because it slow down the performance of server.

In any kind of web application unlimited number of session can be created. It might impact the performance of application if the application is not in clustered environment.

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