The journey of shells started in the 1960s and 1970s when computers had just begun to become more than just calculators. In 1971, Ken Thompson introduced the first Unix shell, which is called the Thompson shell. The shell allowed users to provide commands using natural language like syntax. It was more user-friendly than previous techniques. Then Stephen Bourne developed the Bourne shell which replaced the Thomson Shell as it is more powerful and flexible. However, more advanced shells like Bash(Bourne Again Shell) arrived later.