Tourist or Business Visa
If you are intending on visiting the US for tourism or business purposes then an ESTA visa will usually be sufficient to cover your visit if you are from a country that is part of the Visa Waiver Program. With an ESTA you are able to attend business meetings and conferences provided that your visit is not going to be longer than the 90 day limit.
If you are planning on visiting the US for business purposes but your stay is going to be longer than 90 days then you will need to apply for a different type of visa i.e. a B1 visa. Similarly, the ESTA will not be sufficient if you are travelling for a short course of study, medical treatment or some other purposes in which case a B2 visa may be the appropriate type of visa that you need to acquire.
Take a look at our B1 visa and B2 visa pages to find out more about them and whether you require a B1 visa.