This blog post discusses how multi-tasking enables efficient CPU time-sharing among programs, allowing them to seemingly run simultaneously on a single-core processor. The OS scheduler manages task switching, allowing programs like a music player and a word processor to share CPU time effectively. Context switching is a rapid process that gives the appearance of parallel execution. However, distinct processes have isolated memory spaces, complicating data sharing. Threads within a process, on the other hand, share address space, simplifying communication and resource management. This post also introduces the pthread library for creating threads in C, showcasing the practicality of multi-threading.