This document discusses various types of visas required for entering the United States, including: nonimmigrant visas for temporary visitors; the H-2A visa for temporary agricultural work; the Visa Waiver Program which allows citizens of 38 countries to enter visa-free; and ESTA authorization required for Visa Waiver Program countries. It also notes visa exceptions for Canadian citizens and British Overseas Territories citizens from Bermuda, as well as countries whose citizens are currently barred from US visas.

2.  Certificate issued or a stamp marked (on the
applicant's passport) by the immigration
authorities of a country to indicate that the
applicant's credentials have been verified
and he or she has been granted permission
to enter the country for a temporary stay
within a specified period.
 And some country provide VISA ON
ARRIVAL

3.  Policy:-
Visitors to the United States
must obtain a visa from one of
the United States diplomatic
missions unless they come from one of
the visa-exempt countries or Visa Waiver
Program countries

5.  There are various types of nonimmigrant
visas for temporary visitors to travel to the
U.S., if you are not a U.S. citizen or U.S.
lawful permanent resident.
 The purpose of your intended travel and
other facts will determine what type of visa
is required under U.S. immigration law.
 It's important to have information about the
type of nonimmigrant visa you will need for
travel, and the steps required to apply for
the visa at a U.S. Embassy or Consulate
abroad.

7.  The H-2A visa allows a foreign national entry into
the US for temporary or seasonal agricultural work
for eligible employers under certain conditions
(seasonal job, no available US workers).

8.  Currently, 38 countries have been
selected by the US government for
inclusion in the Visa Waiver Program and
their citizens do not need to acquire a US
visa.
 However, citizens of these countries are
required to obtain an Electronic
authorization: in order to visit the United
States, Puerto Rico, and the US Virgin
Islands

9.  The Electronic System for Travel
Authorization (ESTA) is an automated
system that determines the eligibility of
visitors to travel to the United
States under the Visa Waiver Program

11. 
:- Citizens of Canada do
not require a visa to enter the United
States under most circumstances, and
can work under special simplified
procedure. They may use a NEXUS Card
instead of a passport to enter the country
from Canada, or, if arriving by land or
sea, an Enhanced Drivers License.

12. 
:-British Overseas
Territories citizens with a connection to
Bermuda can enter the United States visa-
free under most circumstances if their
intended stay is less than six months.
the passport must contain one of
the following endorsement stamps: "Holder
is registered as a Bermudian", "Holder
Possesses Bermudian Status" or "Holder is
deemed to possess Bermudian status".

14.  Following the expiration of the Executive Order 13780
on September 24, 2017, President Donald Trump
signed a presidential proclamation suspending the
issuance of visas to nationals of certain countries::
 Iran
 Libya
 North Korea
 Somalia
 Syria
 Venezuela
 Yemen
 Chad

15.  The purpose of their trip is to enter the
U.S. for a specific, intended purpose;
 They plan to remain for a specific, limited
period; and
 They have a residence outside the U.S. as
well as other binding ties which will
ensure their return at the end of their
stay.