What is Oh My Posh?

Oh My Posh is a custom prompt engine for any shell that has the ability to adjust the prompt string with a function or variable.

Here's what my Windows Terminal looks like using the theme stelbent.minimal

Why customize the shell after all?

It all boils down to user preference. Just like how you like to customize and theme your favourite IDE, which is completely optional, you can also customize your terminal if your work revolves around using it, which is also completely optional (also, who doesn't like customization?)