Mauritanian visas require an invitation or sponsor, can take up to several months to process, and must be obtained prior to travel.

Also visas for longer than 90 days require a recent HIV test result certificate in the previous 90 days.

No visas required, I think.

Most non-immigrant visas are for work purposes, and usually require an offer of employment from a US business.

All visas require a sponsor, can take several months to process, and must be obtained prior to arrival.

This visa requires a smaller investment, often in such businesses as laundries or restaurants, and does not stipulate the creation of jobs.

His visa requires him to leave Wednesday.

This special visa requires renewal every three months.

No visas or vaccinations required.

Your visa may also require you to leave the country PDQ after finishing - Korea, for example.