When I started writing TypeScript, I didn't have much of any experience with strongly typed languages. For that reason, it was a bit of a sharp learning curve. Especially, when I was used to JS that just lets you do whatever the heck you want. This is a very basic intro that would have been helpful for me when I started. Hopefully, it's helpful to someone else out there.
This is generally pretty straightforward and easy to read:
const thing: string = "asdf";