I like to think of it like this: For 0 based indexing the punctuation is the indexes/offsets: [ a , b , c ] 0 1 2

I like to think of it like this: For 0 based indexing the punctuation is the indexes/offsets: [ a , b , c ] 0 1 2 3 for 1 based indexing consider the actual elements are the indexes/positions: [ a , b , c ] 1 2 3 In the first case it is non inclusive, ie. elements[0:3] - all items between offset 0 and 3 The second case is inclusive, ie. elements[1:3] - all items including 1 and 3 Personally I don't have an issue with either, they both 'make sense' Where they stop making sense is when you'd mix up the inclusivity ie (for the second case). elements[1:4] - including item 1 not including 4