This is a very, very large topic, with lots of nuances, and it varies by SE.

When I have very general questions like yours I begin always by searching. You can also do a site specific search on only WebmasterWorld posts using any one of the three major SE's.

Have a look up at the top of this page next to the WebmasterWorld logo, and click on the link "site search." Pick a SE, and search on your query (in this case "duplicate content" or "duplicate content filters"). Read to your heart's content.

Then if you have more/specific questions, post them here, or in the appropriate forum if they pertain to a specific SE.

Meanwhile, here are a few to get you started:

[webmasterworld.com...]
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