Can you explain what the big-endian byte order means when storing data in memory?

Big-endian byte order is a method of storing multi-byte numbers in memory, where the most significant byte is stored at the smallest memory address, i.e., at the beginning of the sequence. For example, a 32-bit number 0x12345678 in memory will be stored as:

Address:  0x00  0x01  0x02  0x03
Value:    0x12  0x34  0x56  0x78

This is opposite to little-endian, where the least significant byte is stored first. Big-endian is often used in network protocols (network byte order) and some processor architectures.