Yak Shaving: The process of performing a series of nested tasks to accomplish a goal, each of which seems necessary in context but becomes less and less linked to the original goal.

Technical Debt: The accumulated negative technical results of shortcuts and trade-offs taken in the past on a project, which place a drag on the cost of current and future development on the project.

Bikeshedding: Spending disproportionate time and energy spent over an insignificant or unimportant detail of a larger concern.

Source: Useful tech terms: Yak Shaving, Technical Debt, Bikeshedding