Backstreet Boys were the biggest band in the world for a short while and that period is documented on their first hits compilation, 2001's The Hits: Chapter One.
Twelve years later came Essential Backstreet Boys, a double-disc set that has all 13 songs from The Hits, along with another 16 songs -- generally, songs that came after 2001, when BSB started to slide down the charts.
There were hits -- 2005's "Incomplete," 2007's "Inconsolable" -- that just showed up on the Adult Contemporary charts; a fair approximation of where the group wound up in their second decade.
Essential Backstreet Boys traces this evolution, filling in a few more details of those early hit-making years, which makes this worthwhile for the dedicated fan, but many listeners may find either The Hits, or the variety of budget-line collections released since, to be a better bet as they contain the hits and nothing but.