The standard (and default) port for HTTP<span> servers to listen on is 80, though they can use any port. </span>HTTP<span> is based on the </span>TCP/IP protocols<span>, and is used commonly on the Internet for transmitting web-pages from servers to browsers.</span>
It helps reveal the flow of execution of your program, including results of in-between evaluations. In other words, you can see what your program is doing, and why it takes the decisions it is taking.
If something unexpected happens, the trace will show you the sequence of events that lead to it.
B are primary and C are secondary.
