Which type of memory needs to be constantly recharged to retain its contents?

Dynamic RAM (DRAM) requires constant refreshing to retain its contents because it stores data using capacitors that leak charge over time. Each storage cell in DRAM consists of a capacitor and a transistor; the capacitor holds the bit of data, but it loses its charge quickly. To prevent data loss, the memory controller must regularly refresh the contents by reading the data and rewriting it. This is essential for maintaining data integrity while the power is applied.

Static RAM (SRAM), on the other hand, does not need to be refreshed constantly since it uses a different structure based on bistable latching circuitry to store each bit. Read-Only Memory (ROM) is non-volatile and retains its contents without power, making it fundamentally different from DRAM. Flash memory, although it can be erased and rewritten, also retains data without needing a refresh. Therefore, the unique characteristic of DRAM is its requirement for periodic refreshing to retain the stored information.