Confused

It's essentially the difference between a loop and a conditional statement.

Loops (ex. for-in, while, do-while, for-condition-increment) Loops iterate through a data structure (like an array). Because of this, he's keeping the data structure (array) constant for the loop. This isn't a hard rule, though. There are many cases where the data structure can be a regular variable, that way it can be modifiable later on in the code. This all depends on your program, however, and what you're trying to accomplish with the data. If you're filling your array with data that shouldn't be modified, then of course declare it as a constant. If you want to be able to access and update the array as needed, then declaring it as a regular variable is perfectly fine.

Conditional Statements (ex. if, if/else, switch) The only purpose of a conditional statement is to test whether a given condition is true or false, and branch your program based off of this outcome. Like loops, conditional statements can take both regular variables and constants. However, it's more uncommon to use constants with conditional statements because the constant will be, well, constant, eliminating the need to branch the code in the first place.

For instance, in his example: ```var distance = 5,

he leaves the variable "distance" modifiable, so he can show how different values will produce different outputs in his subsequent if/else statements.

If this variable was a constant:
```let distance = 5,

then the distance would always be 5, making the if/else statements pointless since the code will only ever produce the same output. Sure, you could manually modify the constant yourself. But, this defeats the whole point of programming, which is to make the computer modify the variables for you.

Anyway, I know this was probably more than you were looking for but hope this helps nonetheless.