A lot of people forget that IQ is an anagram of Intelligence Quotient and forget what the term means and how it is defined. The definition of the word intelligence itself is also of importance. IQ is a ratio of your individual score on a standardized test relative to scores by others your own age multiplied by 100, and as such a score of 100 is the average. Intelligence is defined as the ability to acquire knowledge and/or skills and how well they can be applied. AKA how easily and quickly can you both learn new things and how easily and quickly can you apply them once learned. Total knowledge acquired and its application (wisdom/memory) is irrelevant when discussing intelligence. The speed with which one answers questions or solves problems is often an overlooked part of more official tests. Those with a lower intelligence but higher memory can perform just as well in life as the other way around, they just often take longer to learn things, (more time studying) but can often remember them better. Broad spectrum analysis versus focused specialization must also be taken into account. AKA savants that are only good at learning a particular subject versus those that learn all subjects well. Allowances must also be given for those that can learn quickly, but have some disconnect when it is time to use that knowledge, for example those that never test well but can perform related tasks perfectly. Racial and cultural demographics must also be taken into account, which is extremely difficult in "Official" standardized testing. What is common knowledge for one group, may not be for another, such as spacial mechanics or semantics. As someone else alluded to, personal biases of the test creators and proctors also factors in. Many times, though not always, there is a demographic bias. This is why professional organizations, such as Mensa, often encourage those interested in a truer score to take multiple different sanctioned tests and then use the mean average. It is nearly impossible for any specific single test to take all these factors into account.
Online tests are rarely graded on a time quotient, making them useless on this facet alone. They also rarely use an algorithm to compare the age of a test taker to that of all previous test takers so that their "score" is only judged relative to others of equivalent age. The also rarely take demographics of test takers into account. Doing so accurately would require a lot of time and money investment, as well as a starting pool before any scores are possible, due to IQ itself being merely an average ratio. Spacial mechanics skills, such as solving a Rubik's cube, are also nearly impossible to test online. Until we see an all inclusive test that takes all of this into account and from a reliable source, such as Mensa or its affiliates, none of the online tests are anything other than an ego booster or destroyer. Such a test would take numerous hours to complete, and the results would be given in terms of age category and demographics, such as compared to all U.S. born and raised Caucasian test takers from the Midwest that did not grow up in poverty aged between 25 and 30, and other relative distinctions, the tests are meaningless.
To the OP, if you like taking online "IQ" tests, there is nothing wrong with that. Just keep the points I discussed in mind and don't get too ecstatic about a single "great" score or depressed about a single "bad one." If it was a short test that only took a few minutes, the results were processed instantaneously, or there was no or a very short demographics questionnaire, disregard it entirely. If you find that after taking numerous tests that you usually do well above average and are truly that curious, then I would suggest looking into taking official ones. Even so, as stated previously, any one specific test is inconclusive at best regarding being a true representation of how intelligent you may or may not be.
HUGS!
