What is an immigration point system?

The Senate bill will include a point system to sort out and prioritize persons seeking to immigrant – or to change their status from temporary to permanent in the U.S. A pint system is reported to be a keystone for bipartisan support of immigration reform. So, what is it?
I have posted on it before regarding Canada, and to a lesser extent Australia and France.
A sympathetic analysis of the point system concept was presented on May I before the House Judiciary Committee’s subcommittee which is drafting the Senate bill. The presentation was made by Demetrios Papademetriou, President of the Migration Policy Institute.
He believes that a point system can help steer immigration but it should not be a centerpiece.
“Point systems are first and foremost human capital accrual mechanisms” he said. Pints are given to what a country wants to value at a specific point in time among all the possible attributes.
Five criteria tend to be applied in point systems of other countries: education, occupation, work experience, language and age.
Sometimes lower values are applied to these other criteria: employer job offer, prior wages, prior work or educational experience in the country, presence of close relatives, certain special considerations, and involvement in job creation.
Canada started a point system by focusing on areas of shortages of certain jobs (not shortages of workers for jobs). That did not work. It revised the system to focus on broader criteria of economic advancement.
One quarter of Canadian immigrants are processed through its point system; rest immigrant based on traditional criteria.
To some degree a point system shifts the talent search away from employers using temporary visa programs and towards government driven selection processes. One can have a hybrid system of some temporary programs filled by employer sponsorships alongside a point system.
The political advantages of point systems start with their appearing to use quantitative, objective selection criteria to advance clearly defined economic and labor market goals. The system comes in effect with a grand plan seal.
Also, if the point system is designed to focus on long term economic growth, there is less concern about the system causing of a displacement of native workers.
And also, the system appears flexible, adaptable and simple, so that is can be maintained and stay legitimate over time.
A point system can be refined to govern the passage of illegal immigrants into legal status and then