Therefore the data would only be cached in RAM once.

The backing store in RAM is no longer needed at all.

Temporary operating system data is usually kept solely in RAM.

During the first pass the symbol table was built and stored in RAM.

Nothing is written to the hard drive or into the file system, but it's kept in RAM.

If not, should we watch out for applications that store sensitive information in RAM?

The data structures behave as if they were in RAM.

My impression is the 30-minute buffer only exists in RAM.

The table used to look up the appropriate function is stored in RAM.

B+ trees can also be used for data stored in RAM.