Question : what is propagation delay?

Hi experts,

I took up a course on Computer Networking this semester and have tried very hard to understand the terms but so far still very very unclear and would really appreciate a lot if anyone could point out the meaning of the following terms in an EASy to understand.

-Propagation delay,
-Processing Time
-Transmission time

>>What's the different between them? Especially, the propagation delay and the processing time<< I have hard time understanding these two..

Thank You,

Answer : what is propagation delay?

propagation delay refers to the time lag between the departure of a signal from the source and the arrival of the signal at the destination
processor time is the amount of time the CPU is actually executing instructions
Transmission time is at wire-level, there are two distinct delays: transmission and propagation. The propagation time is dependant on both the distance and the speed of the signal through the particular medium. For 10/100/1000 Base-T, this speed is equal (~2x108m/s) as they all employ copper. For these technologies, base rate has no bearing on propagation delay. Conversely, the transmission time is directly related to base rate.