ACT

ACT stands for "American College Testing". It was established in 1959.  It is another popular college admissions test for US students aside from the SAT. Most universities accept ACT and SAT interchangeably.

Here is what an ACT test looks like

Total time is approximately 4 hours (including breaks).

Scoring system: each of the 4 main sections (English, Maths, Reading, and Science) has scores ranging from 1-36.  Then the total score of these 4 sections is then averaged into what is known as the composite score (the overall score which ranges from 1-36). 

There is also another computation known as the sub-score, which is a stand-alone score, separate from calculating the composite score. It is used to indicate your skill in certain parts of the test.

It ranges from 1-18.

For the science section, the total test score is based on all 40 questions. There are no sub-scores in this section.

What's the difference between ACT and SAT in terms of difficulty and what should I choose?

One of the main differences between the ACT and the SAT exams is that the ACT is known to be more straight forward (testing your knowledge rather than your reasoning skill, which is more like the SAT). The format of both tests consists mainly of multiple choices. The difference is that in the ACT there are 4 choices to choose for each question whereas in the SAT there are 5 choices.  Also in the ACT, there is no penalty for choosing the wrong answer, unlike the SAT where 0.25 point is deducted for each wrong answer.  So in the end, you should probe both tests to determine which one is right for you. And once you make your decision, stick with either one and try to improve your score with extra studying and practice.

Useful Link

ACT Schedule and Registration