Refactoring -- Not on the backlog!

As "Technical Debt" grows in a project, a question frequently comes up: should we put refactoring "stories" on the backlog, so they are treated as jobs-to-be-done in the next sprint? Should we have an entire session just for refactoring? In this timeless article Jon Jeffries shares his experience as to how to approach refactoring - specially as the codebase grows and starts to slow down the overall velocity of the team.