Technical debt is any shortcoming in the solution that makes it less than 'good enough' and might create problems in the future. When there's a lot of technical debt, the velocity might decrease in the future because developers have to
deal with the shortcomings. On the other hand, this debt might even remain in the final product and make it harder and more expensive to maintain the product. 'Total cost of ownership' is the combination of production and maintenance
costs of a product.