1. In general, a resource is any hardware or software that is accessible by the computer, network or other object connected to a computer. For example, a printer connected to a network is an example of a shared resource. Another example of a resource may be a network server farm or cluster that allows users to have access to multiple computers to perform complicated tasks.
2. When referring to only the computer a resource or system resource is any of the internal computer components. Most often this refers to the amount of available computer memory. For example, a program may report low system resources, which indicates the computer is running low on available memory and it may be necessary to close some of the open programs.
3. Hardware resources are a hardware devices settings that allow it to communicate with the computer. The most common hardware resources are the DMA, I/O port, IRQ. In the picture below is an example of how a hardware resources could be configured on a Sound Blaster sound card in Windows 98.