are there potential pitfalls to using static methods in a web application (.net)?

Question

From the web app, calls are made to a web service that in turn makes calls to a few static helper classes for filtering and sorting data - trying to think ahead if I will have unexpected behavior with multiple users

Answer 1

Make sure your static methods are thread-safe.

Thread safety fundamentally deals with ensuring that two threads don't access a shared resource in a conflicting manner.

There's a great overview on Wikipedia.

The best tutorial I have ever found about threading in the .NET environment is by Joe Albahari.