Newbie Kid With A Collection

Hello everyone. I don't have any previous experience collecting stamps. Years ago my father gave me this book that has a collection of stamps from all around the world. I have some questions:

- How to tell if a stamp is genuine?

- What determines its value?

- What are the marks on some stamps (such as on the American ones (the curved lines) that I uploaded below, versus the German ones that don't have them. And how does this impact the stamp's value?)

The stamps I will showcase here are American and German ones that I found interesting. (I tried uploading an image of a whole page of them, but it was too big, here are a few examples.):

The wavy lines are machine cancels, meaning the stamp had been on an envelope and served it's purpose (prepayment of postage). Later, someone soaked the stamp off the envelope to be collected by a stamp collector.

The ones without cancels are unused, or what's called "mint." There are stamp collectors for both types of stamps, used and mint.

Welcome.
Don

Value is determined by supply (common or scarce) and demand (popularity) and by condition of the stamp (centering and presence or lack of faults).

As a general rule, mint (unused) stamps are worth more than cancelled (used) stamps. There are some exceptions, such as when a relatively rare stamp was in actual postal use for a very short time. In those cases, the cancellation needs to be from the proper period of use (and the stamp is preferably still on the envelope or postcard) and usually needs to be authenticated. Which brings me to another one of your questions:



Short answer: Compare it with one that is known to be genuine.

There is no easy answer to this question. Some fakes are obvious, others less so. Some "classic" fakes are even worth something. Being able to tell the difference between genuine and fake often requires study, especially when the stamp is genuine and the overprint or cancellation on it is fake.