data structure alignment

When a modern computer reads from or writes to a memory address, it will do this in word sized
chunks (e.g. 4 byte chunks on a 32-bit system).

It includes two issues, data alignment and structure padding.

Data alignment means putting the data at a memory offset equal to some multiple of the word size, which increases the system's performance due to the way the CPU handles memory.

To align the data, it may be necessary to insert some meaningless bytes between the end of the last data structure and the start of the next, which is data structure padding.