The article explores fundamental concepts of computer architecture that developers should be familiar with, focusing on the differences between threads and processes, and their implications for security, memory management, and performance. It explains how processes operate within isolated memory spaces, enhancing security, while threads, sharing the same address space, can pose risks if one crashes. The article also discusses the efficiency of context switching in threads and processes, highlighting how modern CPU hardware and operating systems use techniques such as copy-on-write and paging to manage memory. It further describes the potential performance drawbacks of using too many threads, which can lead to thrashing, a situation where excessive context switching and resource management hinder execution efficiency. The author uses the example of Uber drivers to illustrate the concept of thrashing, emphasizing the importance of optimizing thread management to maximize performance. This is part one of a longer series, with a promise of more insights to follow.