L1 visa is an intracompany transfer visa. It is a permit to work for a company in USA, to which you are transferred from the parent or the sister concern company of your country.
L1 visas is filed by your company, and needs to be approved by the USCIS. The requirements for L1 visa are:
Yes, one can also be given L1 visa, if he is sent to set up an office in US for his company.
In this situation the conditions to be fulfilled are:
The L-1A Visa is for Managers and Executives. A benefit of being on an L-1A visa is the ability to apply for a Green Card (Permanent Residence), without going through the process of Labor Certification, after only one year in L-1A status. The L-1B Visa is for key employees (accountants, computer programmers, etc.).
Read more about the eligibility and benefits of L1 Visa.
For those who have currently applied for this visa or are planning to apply for the visa in the future, here is some useful information on the process.