WPF PIXELS DPI RESOLUTION

I am reading 开发者_运维百科a book on WPF.As with all books, it gives an introduction on the problems the earlier display systems had with them.He refers to terms such as DPI, Pixels, Resolution etc.Is there any place where I can learn about them and about how they are related to each other ?

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DPI is dots per inch.

But in my opinion if you are learning about WPF, these things you are wondering about are not that important other than a quick read on the wikipedia.