To spy on someone’s PC without them knowing, you need to install spyware on it. The application is service-based and runs in the background, which allows staying undetectable. A user gets an online account during the registration. This is the place where spyware delivers the data about someone’s PC.
So, if you want to know what exactly someone is doing at a particular time on their computer, you log in to an online and spy on someone’s computer from there. It doesn’t happen simultaneously. First, the app records data, then delivers to an online account, and then you read it. However, a user sets updates intervals.