Final answer:
The sizeof operator measures the size in bytes of a data type or variable in programming languages like C and C++, helping understand memory usage.
Step-by-step explanation:
The sizeof operator in programming languages like C and C++ gives the size in number of bytes of any data type or variable. This is useful for understanding how much memory a particular data type or variable will occupy in memory. For example, in C, an int is commonly 4 bytes on a 32-bit system, but this size can vary based on the platform and compiler. Thus, sizeof(int) would typically return 4. Knowing the size of data types is critical when you are dealing with low-level memory management.