Tasks vs Stories vs Spikes (oh my!)
Imagine you and I work at a furniture workshop. We build furniture out of wood and place it in a showroom out the front where customers can buy it.
Building a piece of furniture is a story. It translates directly into customer value.
Tasks we might do would include cleaning the workshop and repairing the machinery we use to build the furniture. If you asked the customer what they paid us for, they'd say they paid us for furniture. They don't pay us to clean the workshop, nor do they care how clean it is. However, if we don't clean the workshop for long enough or if we let the machinery break down then it will severely impact our ability to build furniture.
One day a customer comes into the shop and asks us to build a 10 foot tall chair.
We've never built a 10-foot tall chair before. We're not sure if it will fit into the machines or how long it might take to build. So we take some time to measure the machines and cost the materials. We might also write down the steps that might be involved in building a 10 foot tall chair and try to guess how long it would take. This is a spike. Once we have a better idea, we can go back to the customer with a price.
The customer thinks the price is fair and we start building the giganta-chair. It's a lot of work. More than a regular piece of furniture. Building the legs alone is a big job. Building a big chair like this is an epic. The base of the chair might be one story, the arms and back a second, the ladder a third and the final assembly at the customer's location is part 4. Notice we can deliver each of these parts to the customer as they're finished.
Every so often customers bring furniture back to us because a handle fell off or something. These are bugs.
If a piece of furniture is sitting in the showroom unsold for a long enough time we might take it back into the workshop and repaint it to make it more appealing. This is an improvement.
A customer once asked us if a particular table could hold a 500kg fish tank. We weren't sure so we took it into the workshop and ran a test.