The H-1B is a non-immigrant visa which appeared with the passing of the law in 1952 the Immigration and Nationality Act. Basically it allows temporary worker's a visa to the US to individuals of exception ability. A good rule of thumb is that yo must have at least a bachelors degree in order to qualify. Once qualified you can be eligible to stay for up to 6 years under the H 1b status.
The H-1b is a very sought after US visa as it allows you work legally in the USA and you can also seek to get permanent residency called dual intent. On most other temporary visas if you say or do things that indicate that you have Dual Intent and want to become a permmanent resident which is a path to US citizenship, that can be a major red flag and disqualifying you for entrance to the US. sometimes turning you around at the border, even with a valid visa!
Employers that wish to hire someone under the provisions of the H-1B must file a Labor Condition Application which shows that the employee will be paid more than the prevailing wages for that skill set and that it will not affect US Workers negatively, which means that they will not be taking a job away that an American can do, to protect jobs in the USA. An individual cannot apply for themselves, they must have a sponsor company that formally offers them employment.
One of the areas that the US is trying to get more people into the US with H-1b is nurses with specific higher training including nurse supervisors.