English Japan
This visa is issued to a foreign national who has been offered in a temporary position in a specialty occupation. The foreign national has to have at least a Bachelor’s degree or an equivalent that is related to the occupation. An applicant with a high school diploma, as highest level of education, needs at least 12 years of working experience, whereas an applicant with an Associate degree has to have at least 6 years of experience. It is also possible to establish a U.S. company and apply an H-1B through the company. Among other things, it is required to show that the applicant’s educational and/or professional experience are closely related to the job duties, an attainment of a Bachelor’s degree in the specific specialty is a minimum requirement for entry into the occupation, and the employer makes certain attestations on labor conditions such as the attestation to pay H-1B workers the required wage in the region for that type of work. It is usually granted in three-year increments with maximum of six years. If you hold an H or L visa status for 6 years, the government will not grant an extension of H status unless you reside outside of the U.S. for a year or more. This rule does not apply if you file an application for a green card through employment before the end of the 5th year. It is better to file an application in April if your employer is planning to file an H-1B application that is subject to the congressionally mandated cap.
Alternative to H-1B
Congress has reduced an annual H-1B cap to 65,000 starting from the fiscal year 2004.  Accordingly, the number of foreign nationals who are unable to obtain an H-1B has been increasing.  For example, the cap for the fiscal year 2007 has reached within 60 days from the earliest date for which a petitioner may file an H-1B application.  The earliest date to file a cap-subject H-1B for the fiscal year 2008 is April 1, 2007, with the earliest employment start date of October 1, 2007. You may also consider for an alternative if you meet the requirements of one of the following visa categories.
E-1 / E-2
In order to apply for E visas, the nationality of the applicant and that of its U.S. employer has to be the same, because this visa is issued based on a treaty of the applicant’s country and the U.S. For example, if the applicant is a Japanese national, at least 50% of the ownership of the U.S. employer has to be held by Japanese corporations or Japanese nationals who are not permanent residents of the U.S. E-1 visas are issued when more than 50% of the company’s international trade (of goods, services or technology) are engaged between the U.S. and the country of the applicants’ nationality. E-2 visas are issued when the investment of the company is substantial. Unlike the L visa category, E visas do not require to have a branch, parent, subsidiary, or affiliate company outside of the U.S. Also, E visas do not require the filing with the USCIS prior to the application with a U.S. Embassy or Consulate in the applicants’ home country. The applicant has to be either an investor of the U.S. enterprise or to be employed in a supervisory, executive or essential skill capacity for the enterprise. It is also possible to establish a U.S. company and apply an E visa through the company. Unlike the H or L visa categories, E visas can be renewed without limits. A spouse of an E visa status can work in the U.S. with an authorization from the USCIS.
The L visa category is for intracompany transferees who will be employed in the U.S. in a multinational executive, managerial or specialized knowledge capacity. You need an approval from the USCIS prior to the application with a U.S. Embassy or Consulate abroad.  The beneficiary does not need to have a certain educational background; however the beneficiary has to be previously employed for a minimum of one continuous year within the last three outside the U.S. in an executive, managerial or specialized knowledge capacity for a parent, branch, subsidiary, or affiliate of the U.S. operation. The U.S. operation could be a new enterprise with less than one year from the establishment. If you hold an H or L visa status for 7 years (5 years for specialized knowledge capacity) the government will not grant an extension of an L status unless you reside outside of the U.S. for a year or more. A spouse of an L visa status can work in the U.S. with an authorization from the USCIS.
O-1 / O-2
An O-1 is issued to a foreign national who has extraordinary ability in the sciences, arts, education, business or athletics. With regard to motion picture and television productions, the applicant has to demonstrate a record of extraordinary achievement. Also the individual has to seek to enter the U.S. to continue to work in the area of ability. A foreign national cannot self-petition. They can file through a U.S. agent or U.S. employer. O-2 visa classification is for those who will accompany and assist the O-1 visa holder and their skills are not possessed by an immediately available U.S. worker.
Representatives of a foreign media cannot engage in information media activities in the U.S. under the Visa Waiver Program or on B-1 visas.  I visas are for representatives of a foreign media who engage in the production of essentially informational or educational materials, such as news and documentaries, for TV, radio, films, or publications for foreign audiences. On the other hand, the production of commercial entertainment, such as drama and reality shows, and advertising usually do not qualify for I visa activities.
J visa is given to a participant of an exchange program sponsored by a government agency, educational or medical institution, non-profit organization, or for-profit organization.  There are mainly two types of J programs: one with a two-year foreign residency requirement and the other without such a requirement. Foreign nationals subject to the residency requirement are generally prohibited from changing their status to another non-immigrant classification or from obtaining a permanent residence, except for limited circumstances.
This visa category is designed for a trainee to participate in a training program that is not available in the foreign national’s home country. There are only 3000 H-3 visas issued annually. H-3 programs are used in many different fields, but this visa classification is not designed primarily to provide productive employment that is mainly performed by the petitioner’s regular staff.  There are quite a few restrictions on training programs, including the prohibition of using an H-3 program to extend the training of a former student who has used their maximum period of optional practical training.
B-1 visas are issued to travelers to engage in business activities, such as to open a new office in the US, to conduct marketing research, or to attend business conferences, seminars or conventions.  Generally B visas are not issued to foreign nationals who are permitted to enter the U.S. under the Visa Waiver Program unless the length of the intended trip exceeds 90 days.  Under this visa category, it is prohibited to engage in productive employment in the U.S. for a U.S. employer. It is also not permitted to use B visas to perform as journalists. A B-1 visa holder is allowed to stay in the U.S. up to six months, and may extend its stay for up to additional six months under special circumstances. Generally, it is possible to change status from B-1 visa status to other visa status while in the U.S.
Other Type of Visas
There are other kinds of visas available for foreign nationals.
K (visas for fiancé(e)s of U.S. citizens) is discussed in the page for obtaining a green card through family.