In this week’s challenges, we worked with arrays and hashes—2 concepts that may cause some confusion. This post will help to clarify these concepts and their uses. An array is a systematic arrangement of objects, usually in rows or columns. I first came across arrays in matrix algebra; they were called vectors. It was simply a row or column of number in brackets. Arrays in ruby are not limited to numbers only. What's important about arrays, however, is that the order of the objects matters. Let's give an example: Say you have a list of numbers representing grades on class assignments. You might want to work with that array to identify the lowest grade, highest grade, or even apply weights to grades. Rather than searching through the list, using arrays and methods, you can have what you want returned to you. Hashes are similar to arrays, except they use arbitrary keys, or names, in the index of objects and the keys are assigned values. Hashes are collections of these key/value pairs. For example, you may have a grocery list with vegetable, fruit, meat, drink. These would be the keys and their values would be broccoli, apple, chicken, and lemonade. You could use ruby syntax to return to you the type of drink to purchase, or a list of the types of drinks if there were multiple keys called drink. Hopefully, this have provided some insight into arrays and hashes and how they can be used.