R supports all types of data. The simplest type of data is vector, which is one dimensional representation of a string of similar entities. An example of vector is this: a = ("Kolkata","Rome","New York", "London", "Melbourne"). This represents a series of strings (names of cities). Or this, b = (2,3,4,5) – representing a series of numbers. Moving up, a list is also one dimensional, but it consists of a mixture of different types of data. For example, c = (2,"London","YES") is an example of a list, one that contains a number, a string, and a logical YES in it. Extending this concept further, a matrix is two dimensional (or at least n dimensional) that contains only _one_ type of data in it. A data frame is a two dimensional (or n dimensional) entity that contains mix of different data types in it. In terms of statistical data analysis, a data frame is the most commonly encountered rectangular dataset that most people work with.