The principle is easy. First, index all current processors and graphic cards from vendors like Amazon. Then look at benchmarks to judge their real performance. Based on that data recommend finally the best hardware for the budget. This becomes the recommendation.
Ideal for gamers that just want the fastest hardware for their money.
The automatic recommendation is of course not always perfect for the intended usage. That is why it can be modified.
Each block has two buttons with an arrow at its side. With the left one the next best cheaper option gets selected. With the right one he picks the cheapest better option. That works for every block, but the most options exist for the processor and the graphics card.
The controls activated by the button Advanced control the used manufacturer for processor and graphics card. There are AMD and Intel for processor and AMD and Nvidia for the graphic cards.
The minus symbol at the right upper corner of each block deactivates that type of hardware permanently. Its price will be subtracted from the total price and the next recommendation will ignore its costs.
That is useful if some existing parts can be reused, like the case or the power supply,
You lose your modification if you just link to /build?price=…. Create a permalink with the share button instead.
The buttons next to the share button create permalinks as well, but they do not only that: The reddit button shows also the markdown code that can be used for example in /r/buildapc, the BB button shows the recommendation in BB code, and the other buttons are used to share links in social networks.