To be able to enter certain countries such as the US, Australia and Canada you need to have a valid visa as well as your passport. Visas allow border control to know why people are entering a country, what they plan on doing during their stay so to check if they have the correct visa for this and how long they plan on staying in the country. This is for safety and legal purposes. If you plan on working and earning money during your stay in the US then you would need to have a work visa, however if you just plan on going sightseeing and relaxing then you would only need a travel visa. Also if you’re hoping to transit through the US then you would need to obtain a visa. If you’re hoping to travel to the US via air or sea then you would also need to obtain a visa. You qualify to get a visa if you have a valid passport, are a citizen of an eligible country or you plan to stay in the US for a duration which will not exceed the 90 days. Once the visa is applied for and hopefully accepted it means that people can just relax and get ready for their holiday. The application is generally sorted quickly so that it doesn’t cause any issues to those applying for it. As long as you are eligible and qualify for the visa then you shouldn’t have any issues with getting it accepted.
This means once citizens have a valid visa they can then travel all around the United States, hopefully without any issues. The main three reasons people travel to the United States is for business, tourism and transit. If you’re doing any form of business, traveling round the US or transiting through the US, then you must obtain a travel visa. Visas are authorization for citizens to enter the country temporarily, although they do have limited for the stay, when it’s valid from and when it runs out. The visa is required when arriving at the country as its clearance for non-citizens to enter the country. It will be valid for 2 years and whilst it’s valid this means you won’t have to reapply for it during the 2 year period. For Canada you would need a similar visa such as this one – https://canada-eta.co.uk/