ESTA is the best program if you want to travel to the US for a short time. It has been considered as the most convenient process by the people because it is easy to get enrolled in this program, as you have to be compatible with the eligibility criteria given by the homeland security officers. To apply for ESTA, you should have a valid reason to travel, such as for medical treatment, vacations, etc. You do not have to go through the USA embassy to apply for the visa.
If you are planning to immigrate to US and seeking to apply through the ESTA program, you are not eligible to apply as these are for short term trips if have to show your round trip ticket and immigration requires the proper US visa. Moreover, the ESTA program will not even change to the long-term visit.
If have are planning to visit the US and get married over there you can then also stay only for a short time. You cannot convert this ESTA into permanent residency as you can request for the application of citizenship and return within 90 days.
You cannot apply through ESTA if you have decided to get the high school diploma or graduation degree as these programs require a proper study visa. However, if you want to go for summer exchange programs, it is the appropriate way to visit the US.
If you are the colleague of any famous business company and you want to attend the meeting of any business associates, or you are going on behalf of your company to make any deal over there. ESTA is a suitable choice for you. Nevertheless, you have submitted the complete detail regarding the purpose of your visit.