<p>In many places, <code>(1,2,3)</code> (a tuple) and <code>[1,2,3]</code> (a list) can be used interchangeably.</p>

<p>When should I use one or the other, and why?</p>

The list
```
[1,2,3]
```
is dynamic and flexible but that flexibility comes at a speed cost.
The tuple
```
(1,2,3)
```
is fixed (immutable) and therefore faster.