Five years from now I will remember the concept of heuristics, which are mental shortcuts that help us to streamline our thinking and make sense of our world- but heuristics show that we can be fooled easily. More specifically, I think I will remember the representativeness heuristic, which is judging the probability of an event by its superficial similarity to a prototype. People will judge others based on similarities and stereotypes. I know that I have been guilty numerous times in the past of judging others based on their appearance. 
If I were to see someone wearing glasses and reading a book at a library, I would probably assume that he or she is a "nerd". I will keep in mind in the future to try not to judge others before getting to know them. I think I will remember this heuristic five years from now because if there comes a time when I will think about/want to judge someone- I will remember this concept and try not to fit people into stereotypes.
Nice post.