Why can I use the keyword "let" also for a variable name? Shouldn't it be reserved?

I came across this question later on, when I was beginning the chapter “Arrays”. I tried it out and it works, though it doensn’t work with the keyword ‘var’, which seems to be reserved indeed.

Also, when I just use a name for a variable, but don’t specify if it should be ‘let’, ‘var’ or ‘const’, it still works to initialize it with a value and log that value to the console. Is there a ‘let’ or ‘var’ automatically assigned to this variable then?

Hello! Can you post the code you’re referring to, please? Make sure to format it as of this thread.