A standardized test called the International English Language Testing System (IELTS) is used to evaluate a candidate's language proficiency in situations when English is the primary medium of communication, such as when they are studying or working. It assesses one's ability to read, write, talk, and listen.

Another standardized test to gauge English language competency is the Pearson Test of English (PTE). It evaluates proficiency in speaking, reading, writing, and listening through computer-based testing techniques.

An online proficiency examination that assesses a test taker's English proficiency is called the Duolingo English examination. It evaluates proficiency in speaking, writing, reading, and listening via a series of Duolingo exercises.

The decision is based on a number of variables, such as your preferences, the test availability in your location, and the prerequisites of the school or organization you are applying to. While certain institutions could have particular preferences, others might allow several tests. It's a good idea to find out what your intended institution or organization requires.

The IELTS is graded using a nine-band system, where each band represents an English competence level. In addition to an overall band score, test takers receive individual scores for each of the four sections—speaking, writing, reading, and listening.

A scoring system based on a range of 10 to 90 is used by the PTE. There are distinct scores for the reading, writing, speaking, and listening sections. The performance in each segment counts toward the final score.

A score ranging from 10 to 160 is assigned for the Duolingo English Test. The difficulty of the questions and the overall performance in speaking, writing, reading, and listening are taken into account when calculating scores.

Depending on personal preferences and learning styles, several preparation techniques are used. You can take practice exams, use official study materials from the test administrators, get advice from tutors or language schools, and use online resources including websites and apps that give study guides and materials.

Every test has a different validity period for scores. Results from the PTE, Duolingo English Test, and IELTS are usually good for two years after they are obtained. But, as they can have certain requirements, it is crucial to confirm the validity period with the institutions or organizations you are applying to.

Yes, if you're not happy with your results, you can retake these exams. You will have to reapply and pay the test price, and there might be limitations on when you can retake the exam. It is imperative that you review the retake rules for the specific test you intend to retake.