The PC is now an economic and common equipment at home or office. To interface it to the real world is a step in learning Automation and Robotics. In Automation we have both Industrial and Home.
Experimenting with Home Automation and Building PC based Instruments is the first step. An Electronics card needs to be interfaced by Serial, Parallel or USB Ports.
A computer can be used to control or automate systems. From turning lights on/off at your home to shutting down motors or heaters in industries. Speed control and PID Control too.
PC based Instrumentation is easy to implement using USB Devices and Plugin Cards for Test and Measurement. Most instruments can communicate with PC on the GPIB interface.
USB interfaces have made such PC based Data Acquisition and Controls much easier. In the early days it was Printer Port and Serial Port. The future is for Wireless Device Networking.
When Intelligent Devices (embedded systems) are privately and securely networked, it is called the Intranet of Things. This is like a Home-Office-Business private closed Cloud. This is ideal for Home and Infrastructure Automation and even Big Business or SMB Automation.
This can get you started too. The few examples above show an instrumentation – Logic Analyzer ‘Like’ interface and a relay-display driver circuit. They are examples i tried for students to try out and learn.