Web scraping is a process of retrieving of desired data from websites. It’s being used when a site from which you want to retrieve some data does not have API or another designed way to do it.
P.S.: For your information, if the target site noticeably change its layout, the website parser code, attached to it, probably will be broken. It can be fixed fast if a change was moderate, or should be almost completely rewritten otherwise, if the paradigm of data retrieving was changed.