checks to see is if what is run in the function is the data type given - ANS-is.x
allow you to store data as a collection of variables, potentially different types - ANS-data frames
good ways to inspect data frames - ANS-head() and summary()
displays the internal structure - ANS-str()
extracts the names of a data frame - ANS-names()
dimensions of a data frame - ANS-dim(), nrow(), ncol()
dataframe[row,column] - ANS-subsetting data frames