https://www.google.com/search?q=what+is+page+tracks+extents+modified+since+last+full+backup
First, second, third and fourth hits.
https://www.google.com/search?q=What+needs+to+be+done+to+recover+a+database+up+to+point+of+failure
First, second, third, fourth and fifth hits.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability