about the us visa policy and there other visa' program

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.