Tax
Worldwide taxation
Worldwide taxation is a system under which a country taxes its residents on all of their income wherever it arises, giving relief for foreign tax paid through a credit or exemption. Most developed countries tax residents this way, and the United States taxes its citizens this way regardless of residence.
In plain terms: The country taxes everything you earn anywhere, and gives you credit for tax paid elsewhere.
Why it matters
This is the default position most founders start from, and the reason relocation rather than restructuring is what changes a tax bill. No company structure removes worldwide taxation of the person who controls it.
Common misunderstanding
Believing an offshore company defers it. Controlled-foreign-company rules exist precisely to tax the profits of a low-taxed controlled subsidiary as they arise, whether or not anything is distributed.