Relocating to the USA as a doctor

Medical professionals relocating to practice in other countries is not an unusual occurrence, but finding relevant, helpful information is. If you are a UK medical student or doctor (junior doctor, specialist, consultant or GP) who wants to relocate as a doctor to the US, this guide is for you.
 
Information included:
Healthcare system and structure
Eligibility and exams - USMLEs & OET
Postgraduate training and finding a job - residency
Immigration and visas
Lifestyle
Checklist of the things you need to get done before relocating (with approximate time periods)
 
UPDATE (2022):
Example entry routes and standard training of doctors in the country
Social media account recommendations (where available)
AND overall top tips for securing a post as an IMG