Random Access Memory $($RAM$)$ is the computer's temporary storage space. What other characteristics and true about the RAM memory?

RAM is considered volatile memory because when the computer is turned off, the temporary stored data disappears.

RAM is considered nonvolatile memory because the computer never clears the data from the temporary storage when the computer is turned off.

RAM memory is not as important the Read$-$Only Memory $($ROM$)$ since its data is stored in a temporary area.

The RAM memory is so expensive to install that most user never upgrade the RAM memory.