How are e-catalog sites made?

Question

Web development

Good day.
After another e-catalog ad on YouTube, I thought: how is such functionality implemented?
I just want to understand the point. Are the data taken from stores in advance and entered into their database, and then displayed in the usual way?
If so, what about price changes, for example, or with the status "in stock/out of stock"?
Is it all manual work of managers or can it be automated?

Answer 1

See how CPA providers work, for example admitad , actionpay .
In short: