According to EASA OPS:

"FLIGHT RECORDER" means any type of recorder that is installed on the aircraft for the purpose of facilitating accident or incident safety investigations;

In addition,
a flight recorder may be crash-protected or lightweight and may be deployable or not.

Crash-protected flight recorders are capable of withstanding very severe crash conditions such as those encountered during some accidents of large aeroplanes and large helicopters.

Crash-protected flight recorders comprise one or more of the following systems:

• a flight data recorder (FDR),
• a cockpit voice recorder (CVR),
• an airborne image recorder (AIR), or
• a data link recorder (DLR).

Lightweight flight recorders are usually designed to meet less demanding requirements than crash-protected flight recorders, which allows them to be lighter. A non-deployable flight recorder is permanently attached to the aircraft. A deployable flight recorder includes a part that is capable of automatically deploying from the aircraft.

More Specifically,

"COCKPIT VOICE RECORDER (CVR)" means a crash-protected flight recorder that uses a combination of microphones and other audio and digital inputs to collect and record the aural environment of the flight crew compartment and communications to, from and between the flight crew members.

"FLIGHT DATA RECORDER (FDR)" means a crash-protected flight recorder that uses a combination of data sources to collect and record parameters that reflect the state and performance of the aircraft.

Finally, according to ICAO Annex 6 Part I, the flight data recorder must be located in the aircraft as far to the rear as practicable.

This helps enhance the recorder's chances of survival in a crash and facilitates the retrieval of crucial flight data for investigative purposes.