Tax Liens Question from a newbie!!

[Bo McDonald]

Hey all! New here and excited to learn and dive in!

We’re looking at County websites and seeing properties for pennies on the dollar due to tax liens. Can someone explain, or point me in the right direction of the god the bad and the ugly about going this route? 
For the prices we’re seeing them I’m assuming there’s some type of stipulations on buying these to use as investment properties?

Thank you all!