Is memorization necessary in learning computer science?
It's hard to answer what you &quot;need&quot;, as that depends on your purpose, and hard to answer this question concretely, as it is very broad.  I recommend you focus on learning concepts and ideas, as these are more likely to be of lasting use.  Sometimes, though, to understand how some interesting capability is achieved, you will need to understand the details of how it is implemented.  In general, if you pick a good textbook, then it's likely that there will be a lot of worthwhile material in there.  Saying much more might require getting into specifics.