An employer can sponsor its employee's Green card. It is a multi step process, which involves certain document work confined by few rules and regulations.

There are few categories for granting permanent residence to the foreign nationals, based on employment skills.

Employer based green card categories are:

EB1, EB2, EB3, EB4, EB5.

Most of the technical workers fall under first 3 categories.

i) EB1: employee with extraordinary ability in the science, arts, education, business or athletics, professors, researchers and Ph.D. holders etc. falls under this category.

It also includes people working in US as managers and executives on international transfer basis (Company transfer L1 holder)

(ii) EB2: This includes employee with extra ability in the field of science, arts or business, and advanced degree professionals (PG. degree holder).

(iii) EB3: This includes professionals with Bachelor/ Graduate degree, and other skilled workers.

Employment based green card is a 4 step process:

It's a sequential step wise process.

Step 1: Labor Certification

Application (ETA-750) submission through your employer to DOL (Department of labor).

Step 2: Petition for immigration I-140

Your employer files Application (I-140 ) to INS.

Step 3: Adjustment of Status ( I-485) OR Consular Processing

File I-485 and other supporting documents with INS, for yourself and family within USA.

At this time you can also file for EAD ( Employment Authorization Document) and AP ( Advance Parol or Travel Document) , once you file for 485, you will be required to do fingerprinting.

In this case Step 2 and 3 can go parallel, known as concurrent filing, however 485 can't be approved without approval of I40.

OR

Take consular processing Interview at a US Consulates in your Home Country.

Step 4: Finally

Get the stamping in your passport and Receiving the Plastic card.

Note: The overall process is time consuming, as involves formalities and lot of paper work. It is granted against per year Quota/per country/per category. Another constraint is that a person applying for a green card needs to stick with the company, through which his/her green card is getting processed, till he gets his Green card. Otherwise he loses the process, and needs to apply for a fresh application from the beginning.