Sometimes it's tough to explain what a certain poet's calling card is. But with Cummings, that's no problem at all. For starters, the guy constantly uses lower-case letters in places that call for upper-case ones. Cummings is one of the few poets who does this in a lot of his poetry, instead of just using it as a novelty. There are several reasons he might do this. For starters, the lack of capitals gives his poetry a casual and rushed feeling, as if he just wrote the whole thing in a text message. Second, he might be rebelling against the idea that some things in life (like human names) deserve capitals but others don't.
On top of his lack of capital letters, Cummings likes to take normal phrases and then scramble the syntax, switching some of the words around as though he's writing his poems with magnets on his fridge. Put it all together and you've got something that's uniquely Cummings.