And then, you learned about it: M-x shell.
It was all just text. Why did you need another application for it? Why should only the shell prompt be editable? Why can’t I move my cursor up a few lines to where the last command spewed out its results? All these problems simply disappear when your shell (or shells) simply becomes another Emacs buffer, upon which all of the text manipulation power of Emacs can be brought to bear. — Blurring the lines between shell and editor