Here's how it works here (Leon County, FL).
Owner fails to pay property taxes on time
A tax certificate is sold via auction. The auction is actually bidding down the interest rate on the certificate - whoever is willing to accept the lowest return wins.
Whoever wins the auction pays the amount of the back taxes and now owns the tax certificate. I'm not sure if the certificates can be transferred.
The owner may redeem the certificate, paying the face value + interest + fees. The certificate holder thus gets a return in the amount of the interest.
If the owner does not redeem the certificate, the certificate holder can force the sale of the property. The certificate will be resolved if / when the property is sold. The certificate holder can buy the property at the auction, but so can anyone else.
Now, most properties are worth far more than any back taxes on them, so the owner will typically redeem the certificate in relatively short order. So a lot of the investors in the certificate look at these things as more or less guaranteed returns.
Cursory reading of the sheriff's office in Morgantown's website indicates it may be a similar process there, but you should do a lot of research if you want to get into this type of investing.