Hey Alex! «περισσότερο» is an adverb which means that describes the verb of the phrase. Depending on the context "περισσότερο" can mean "more" or " the most": When you are comparing something it means "more": Συμπαθώ τη Μαρία περισσότερο από τον Γιάννη(= I like Maria more than Yannee)[here the "more" is an adverb so it describes the verb "i like"] When you want to ask In english "the most".(remember again that here "the most" describes the verb!!!): Which candies do you like the most(= ποιες καραμέλες σου αρέσουν περισσότερο)[again the same thing the "the most describes the verb "like"] On the other side... περισσότερος,περισσότερη,περισσότερη is an adjective and describes nouns, an so IT HAS TO AGREE with the noun that describes: οι περισσότεροι άνθρωποι (=Most people are bad) [here the "most" describes the "noun" , so it's an adjective!] Ποιος είναι ο περισσότερος χρόνος που πέρασε κανείς στο διάστημα;(= What's the most time spent in space?)[here, again, "the most" describe the noun "time", so it's an adjective] I hope this helps! Kind regards, Stergios Efes