Composite Data Type: In addition to predefined type, VHDL also allow us to use  array and record types in our VHDL designs. This can provide us with a more structured design which is easier to maintain. These are of two types: Array Record: records are like structures in C language. They allow us to use different types Array: An array is a collection / group of elements of the same type as a single object. Array can be of any type In VHDL. Array can be one dimension, two dimension and multi dimension.  Syntax: type <type_name> is array (<range> ) of <type> ; the <range> field in the above example can be built using the downto and to VHDL keywords Type of Arrays Constrained type array Unconstrained