The L1 visa is a non-immigrant visa that allows foreign companies to transfer certain employees to a related US company. Here are some key points about the L1 visa:

• The L1 visa is a temporary work and residence permit for the United States.
• The US company must be a parent/subsidiary, branch office, or affiliate of the foreign company.
• The L1 visa has two categories: L1A visa for managers or executives, and L1B visa for specialized knowledge workers.
• The employee must have worked for the corporation for one continuous 12-month period in the previous 36 months.
• The L1 visa is a dual-intent visa, meaning that the employee may have the intent to temporarily remain in the United States while simultaneously having the intent to possibly immigrate to the United States and become a lawful permanent resident in the future.
• Spouses of L-1 visa holders are allowed to work without restriction in the US (using an L-2 visa) incident to status, and the L-1 visa may legally be used as a stepping stone to a green card under the doctrine of dual intent.
• The L1 visa is company-based, meaning that the US company officially files the application for future employees.

Overall, the L1 visa is a powerful immigration option for people looking to live and work in the USA, and it allows foreign businesses to transfer certain employees to a related US company.