What is in-transit inventory?

One important element of transportation is the occurrence of in-transit inventory. This Discussion has you connect in-transit inventory to other parts of transportation.

Please answer the following:

-What is in-transit inventory? How does this concept relate to transportation as a whole?
-How is in-transit inventory effectively tracked?
-How does in-transit inventory contribute to greater functionality for warehouse management?

Make sure you are supporting your answers fully and that your source research is identified with citations and references.