In C an array is a collection of elements of the same data type that are stored in contiguous memory locations. It is declared using the following syntax: datatype arrayName[arraySize]; Here `datatype` represents the type of elements in the array `arrayName` is the name of the array and `arraySize` is the number of elements the array can hold. For example to declare an array of integers with 5 elements you can use the following code: int numbers[5]; You can also initialize the array at the time of declaration: int numbers[5] = {1 2 3 4 5}; To access individual elements in the array you use the array name followed by the index in square brackets. The index starts from 0 so to access the first element of the array you would use `numbers[0]` the second element would be `numbers[1]` and so on. You can also assign values to individual elements of the array using the assignment operator like this: numbers[2] = 10; Arrays can be used in loops functions and other programming constructs to store and manipulate multiple values efficiently.