Why is my checkout in my multi store setup behind the url “/default/”?

Question

We have an API plugin and I'm currently testing it with multiple store fronts, but I've noticed that it gets put behind the URL part /default/ instead of just starting at the "root" of the url. The same goes for the /checkout/onepage, this becomes /default/checkout/onepage.
Why is this and how can I disable it?

Answer 1

Most probably you have "Add Store Code to Urls" set to "Yes".
Go to the backend to System->Configuration->Web->Url Options and change it to No.