Check all downloaded files c#

Question

I am trying to create " a little antivirus" but i'm having trouble to understand how does the antivirus know what recent downloads are , for example avast starts analyzing an exe less than one second after i finish downloading it.
but how does it know that a file was downloaded? if there any way to have this comportement using c#? ( with any version of dot net ) if anyone is facing the same problem , found what i needed here : Using FileSystemWatcher to monitor a directory

Answer 1

Keyword: FileSystemWatcher

With this information provided, you should be able to experiment :)