It started with the search engine and followed by all Google's services, including but certainly not limited to Blogger, Adwords, Play store, Gmail and so on. So Chinese students who were applying to foreign universities with a Gmail account would wake up one day and find they had difficulty accessing their own mailboxes. (Don't ask me how I knew it.)

Last time I checked the only Google service available now seems to be the Google Translate.

One project monitors how many popluar sites are blocked in China:

https://en.greatfire.org/analyzer

Tor is also blocked so it takes a considerable amount of effort to make it work. VPNs and other measures (socket proxy, etc.) work but they're also sinfully slow, and it breaks all the time.

The most common search engine there is Baidu: https://baidu.com. Bing has some market share as well.