Schemas and data independence

What is the difference between external,internal and conceptual schemas? How are these differences in layers related to the concepts of logical and physical data independence? Can you related to your professional experience on the topic using the companies you are working for or simply personal life $($like purchasing from Amazon.com$)?$ Who would be the important stakeholders for different layers? Interesting readings to the topic? Anything relatable you want to share? How would the age of big data and data analytics would $($or would not$)$ blur the lings of the layers?