In February 2013, Sen. Jeff Merkley (D-Ore.) sat down with The Huffington Post's Ryan Grim to explain the origins and the long, contentious history of the filibuster.
Merkley spent several months advocating for an end to the silent filibuster earlier this year.
The Senate began a new debate over reforming the filibuster at 10:40 Thursday morning. Democrats have stood in lockstep behind Senate Majority Leader Harry Reid (D-Nev.), though the process on the floor will take time to unfold.
"You will regret this," warned Senate Minority Leader Mitch McConnell (R-Ky.). "You may regret it a lot sooner than you think."
Watch Merkley break down the filibuster above.