MBA is a professional program for those who want to acquire new skills to boost their career. MBA programs require several years of professional experience (at least 3-5), while Executive MBA may be even more demanding in terms of your professional achievements. MBA is very focused degree with clear objective: to boost your career by learning useful skills and networking. The latter is one of the most important reasons to start an MBA degree: you will probably meet dozens of successful people with similar career paths and aspirations, which could be extremely useful in your future career. Best business schools have very diverse student body: you will meet students and future colleages from all over the world.
Prospective students may choose between full-time and part-time MBA: the first option usually takes one or two years of study and you have to spend all this time (except for summer) on the campus of your university. The second option allows you to continue to work: you have to visit your university several times per year for intensive classes and exams. Various options and specializations exist for MBA degrees, including Strategy, Finance, Marketing, HR and many others. Full-time MBA programs typically include summer internship: many companies, especially in the US, have special development programs for MBA students and graduates.
In the United States, as well as in many other countries it is often possible to pursue a double degree with some other schools at the university of your choice. One of the most prestigious options is to get your MBA along with Law School degree. However, the number of places on this programs is typically very limited.
Prospective students will usually have to provide GMAT results (some business schools may also accept GRE), as well as their university transcripts, letters of recommendation and motivation letter. Unlike for undergraduate and PhD programs, your work experience is one of the most important part of you application for an MBA program. It's very important to explain to admission comitee why exactly do you need to get this degree and how it helps you to achieve your professional goals. Moreover, you have to demostrante why you personal experience is valuable and interesting for other students in the class. Leading business schoold often invite short-listed candidates for an interview, so you should be ready to present you personal story and motivation in the most persuasive way.