Many prestigious companies and universities will ask for English accreditation exams so you can prove your fluency in English grammar, fluency, and comprehension.
You may be asked to take either the TOEIC or the TOEFL. The TOEIC is used to test English skills for the work environment. The TOEFL, on the other hand, tests English skills for the academic environment. Most colleges and universities will ask for your TOEFL scores as part of your application.
TOEFL recently implemented the iBT, which allows you to take the exam on the Internet. It will eventually replace the current systems, the paper-based (which has a maximum score of 677) or the computer-based (which has a maximum score of 300). Unlike the two tests, the iBT only has a score of 120.
Other organizations may ask you to take the IELTS or the International English Language Testing System. Cambridge gives this test in partnership with the British Council. It is often required for admission into major colleges or universities, immigration, or even employment.
The IELTS has several sections: speaking, writing, reading, and listening. The highest score is 9. The difficulty level varies on whether or not you are taking the general or the academic option.
These academic tests should not be seen as small application requirements that you have to get over and done with. There is a reason why colleges and universities put such a high premium on English grammar and comprehension. Without the ability to understand what you read or hear, or communicate your ideas in a structured and logical way, then you will not be able to keep up with college-level courses.
Do remember that the texts in colleges and universities are often difficult to understand, and a typical reading assignment may cover several chapters. If you are not fluent in English or take several hours to read a few short paragraphs, the workload will be impossible, and you will probably fail. The tests are not only for the academic institutions benefit, but yours. If you receive a low score, even if you pass, then this is a sign that you should take new English grammar and comprehension classes to enable you to keep up with the rigorous academic standards of the schools you have applied to.