Ok, I presume that vacuum is simply the sucking in of air on a given line or hose.

With that said I have the following question:

1) If I want to check to see if a particular hose is pulling vacuum, will I or will I not be able to put my finger over the hose at idle to see if that hose is pulling vacuum, or would I have to buy a vacuum gauge and connect it to that hose to see if it is pulling a vacuum. In other words, is vacuum strong enough to feel with your finger at idle?

2) If vacuum is something that can be felt at idle, then what is the most reliable vacuum source on a car to get a feel for what vacuum is?

Thanks!