Didn't post here in a long time , this will be about storing game data.
There are a lot of options on how to store your game data structures:
files (json,xml,yaml , custom etc)
databases , nosql dbs
memory (if no persistence needed)
Also if you use an engine it could provide its own way of storing data.
Choosing a good way to do persistence is important.
This depends on lots of factors like game type, complexity of data structures etc
Ill