Time to live (TTL)
Not to be confused with the TTL serial protocol.
TTL is a mechanism which limits the lifespan or lifetime of data in a computer or network.
Learned in ECE358.
From here, they say “TTL (Transistor Transistor Logic) is not a protocol. It’s an older technology for digital logic, but the name is often used to refer to the 5 V supply voltage, often incorrectly referring to what should be called UART.”