[Lordstan]

Your innocent question can spark a powder keg of opinions, so let me give a brief primer.
I am a fish at the lower end of the pool when it comes to vintage photography, but these are my experiences.

Vintage Photos are very cool to collect.
Prior to getting too involved with expensive pictures, make sure you read both David Cycleback's website and The Yee/Fogel book.
Both offer outstanding information that will educate you about all different aspects of collecting vintage phots.

Henry Yee and Marshall Fogel co wrote the book, noted in Graig's post, which first proposed the Type classification system for photography. Currently, they are the two gentlemen who do the authenticating for PSA's service.
David Cycleback has a long history and credits regarding photgraphy and art identicfication and classification. As of the last time I looked, he was the authenticator for Beckett. They offer the same grading and evaluation services for pictures as PSA, using the same "Type" system.

On this board you will find differences in opinion on the merit and utility of the "Type" classification system. I think most of us realize that the system isn't perfect, but a large number of us, including myself feel that it at least offers some semblance of organization/classification as compared to what was done previously. I am not going to go into the long debate on the merits/flaws as you can search for "type" and see all the previous threads detailing everyone's opinion.

As an additional way to learn would be to do a search for "Show your" on the board. There have been many posts like "Show your Babe Ruth items" and others. These were all started by Kingofclout, who happens to be one of the biggest vintage photo collectors on the board. These threads are great sources of discussions and showing off of many of the tremendous photos in everyone's collections on the board.

For a vintage photo collector, this place is fantastic. You will see some incredible pictures on the board.

Hope that helps,
Mark

Also to answer Scott's question:
I agree with you about the slabbing. I personally don't care for it. I do find the "type" system to be helpful. In my mind, the good or bad value of the system is separate that the value of the slabbing.