What is the role of garbage collector in Java?
Garbage collector keeps a track of all unused (or which are not referenced) object in a java program. For example: Lets allocate an object: Object obj = new Object(); // New allocates memory of Object's size. Now, once the program is over, we need to remove the memory allocated by the above statement. This is done by garbage collector so programs don't have to take the burden of freeing the unused memory.
What is a router ?
A Router is a mixture of hardware and software that connects two remotely independent networks together. For example, let there be two networks: Network 1 with nodes A, B and C connected locally (i.e. they can communicate with each other but not to nodes in any other network) and Network 2 with nodes D, E and F connected locally. Now, if place a router between Network 1 and Network 2, all the nodes (A-F) will be able to communicate with each other.
What is the role of # in a C Program ?
# symbol is used to include the prebuilt C libraries and make them available for use in your program. For example, printf function defined in stdio.h can be used to print data on the console/screen. Now, by writing #include "stdio.h" in starting of your C program you can use this function and use it for printing anything on the screen.