Introducing requirements engineering

From a purely metaphorical perspective, if an algorithm is similar to a food recipe, a software requirement is the order we place at a restaurant. But the similarity probably ends here. When we order our food, we pick a specific dish from a discrete list of options, possibly with some small amount of fine tuning.

Also, continuing with our example, the software requirement has a longer and more complex life cycle (think about the testing and evolution of the requirement itself), while the food order is very well timeboxed: the customer places the order and receives the food. In the worst case, the customer will dislike the food received (like a user acceptance test going wrong), but it's unusual to evolve or change the order. Otherwise, everything is okay when the customer is happy and the cook has done a great job (at least for that particular customer). Once again, unlike the software requirement life cycle, you will likely end up with...