lock keyword in C#

Question

I understand the main function of the lock key word from MSDN

lock Statement (C# Reference)

The lock keyword marks a statement block as

Answer 1

Bear in mind that there might be reasons why your application is not as single-threaded as you think. Async I/O in .NET may well call-back on a pool thread, for example, as do some of the various timer classes (not the Windows Forms Timer, though).