Hello Ordinary Guy, welcome to Stamp Community!

I agree that cancels and postmarks and special postal markings add value to a postcard or any other piece of mail.
When I started collecting years ago I was just interested in the stamps alone and would do damage to letters and postcards just to get at the stamps. Now, after years of having fun with stamps I am finally noticing the other markings like cancels on them

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You or another can have an interest in certain eras of postmarks, certain areas or localities, certain historical names or dates, even birthdays or calendar making of postmark dates.
They may be ordinary to some but now I am realizing the importance of postal history, as it is called, and the collecting and study of postmarks or marcophilately.
It is reallu nice also to have a special reentry stamp or error or variety stamp on cover or postcard too.