The change action functions exactly the same as delete but with one major difference: it puts you in Insert Mode after doing the delete. This is helpful when you want to delete text then immediately start adding new text.
c<motion> will change the text specified by that motion.
cw changes a word.
c$ changes to the end of a line
c0 changes to the beginning of a line
C will change text to the end of the current line
ct<character> changes up till that character
cf<character> changes up to (and including) that character