What is the difference between a file header and a file name extension?

What is the difference between a file header and a file name extension? Which is more useful to an investigator (more reliable)?

4. List five common file name extensions used for images and videos.

5. What is a file path and why is it important to high-tech crime investigators?

6. An operating system keeps track of several different file properties for each data file. List the different file properties and discuss the importance of the Date Modified versus Date Accessed information.