Because there is more than one column in the table, we denote this by collecting the columns into a list, which is delimited by parentheses. This entire list is given the name columns. The entries in the list are the column dictionaries, or collections of attributes specific to each column.
A distinction is made between these two types of collection: lists and dictionaries. A list is an ordered array of elements, while a dictionary is an unordered collection of unique keys with values. A value may be a simple string, or another dictionary or array. Most of the values in this example are strings. The value of the columns key is an array. Later we will see uses for values that are dictionaries.
We add the dictionary of keys and values representing the second column as the second element of the columns list.
