Learn about data types, the building blocks of programming. 

Data Types

_Data_ is a basic unit in programming. Without data, we couldn't write any programs! But what *is* data? We may be familiar with data as information, or facts. In computing, data is the pieces of information that we use to build programs, like the numbers in a calculation, or the text printed to a screen. 

_Data types_ are exactly what they sound like: different types of data. Data types tell us about the data, including how it can be stored and what types of operations we can perform. For example, we can write a program that squares numbers, but it wouldn't be able to square a word.

In programming, there's a special group of data types called _primitives_. Primitives are the most basic data types, so basic that you can find them in pretty much every programming language. They include:

- Numbers
- Strings
- Boolean values (True or False)

In the following exercises, we'll dig a little deeper into each primitive data type and what you generally can (and can't do) with each one. 

Introduction to Data Types

So far you've learned about three different data types:
- numbers
- strings
- booleans 

Let's put your knowledge to work! 

In the code editor, we've listed three variables, each equal to a different datatype. Try choosing a function and see what it outputs. 

Putting it All Together

But what if we want to work with data that isn't a number? We can represent other forms of data as a _string_.

Strings are any sequence of characters (letters, spaces, numbers, or symbols). While almost anything can be a string, they are typically used to represent text or speech. Similar to how we represent speech in writing, we surround strings with single (`'...'`) or double quotes (`"..."`). 

But why the name _strings_? Strings are a sequence of symbols, so we can think of the characters being strung together, like beads in a necklace. 

So, what can we use strings for? 
- To display data that uses text or symbols, like printing our name to the screen. 
- To add or remove text. Since strings are a linear sequence of characters, we can break strings into even smaller strings, or combine strings to make longer ones. 
- To modify characters. For example, we could capitalize the first letter of every word in a string if we wanted to turn it into a title. 
- To let the computer communicate with us in a "human-readable" way, like displaying the rules of an online game. 

Strings may sometimes look similar to other data types. But it's important to remember that even if a number looks like a number, or a boolean looks like a boolean, it's good to check that it's not a string &mdash; or else you won't be able to use it correctly! 

Take the following string: `'20'`. The string `'20'` is different from the numerical value of `20`. While they appear to be the same, a computer would see the first as two characters: `'2'` and `'0'`, while the second contains the numerical value of `20`.

Strings

Congrats! Now you know the building blocks of most programming languages and should start to have an idea about the types of simple programs that you could write.

In this lesson, we learned:

- Categorizing information using _data types_ is a way for a computer to distinguish different types of input.
-  _Primitives_ are the simplest data types and are shared across many programming languages. They include:
 - _Numbers_ &mdash; values that allow us to do calculations and keep count.
 - _Strings_ &mdash; a sequence of characters or symbols often used to denote text.
 - _Booleans_ &mdash; logical values that represent the idea of true or false.

Data Types Review

This next data type has a special importance to computing. _Boolean values_ represent the logical ideas of true and false. 

Booleans, unlike numbers or strings, only have two values: `true` and `false`. The term boolean comes from the inventor of a specific form of logic, <a href="https://en.wikipedia.org/wiki/George_Boole" target="_blank">George Boole</a>. Logic is important to computer science because it is an early attempt at translating the human capacity for reason to computers.

So, what do we use booleans for?
- To determine validity. For example, we want to know whether a meme is viral. If it's been viewed more than 50 million times in less than a week, we'd say that it's true that it went viral.
- To make decisions. For example, if I get an email, the program checks that the email is new and it displays at the top of my inbox. 

Because booleans act as binary opposites, we can think of them in a myriad of ways, like on and off, yes and no, sometimes even 1 and 0. 

While we use the words `true` and `false` to represent boolean values, it's important to remember that they are different from the strings `'true'` and `'false'`.

Boolean

_Numbers_ are the original data type. The earliest computers communicated only in numbers, using <a href="https://cs.brown.edu/~adf/programming_languages.html" target="_blank">binary computation</a>. 

We no longer just program using numbers, but numbers still have special properties and are used to do the following:

- _Describe_ &mdash; numbers are used to express value: what is the frequency of a sound wave? We can express that in a number, such as 800hz. 
- _Calculate_ &mdash; numbers are used in calculations: what's the distance between the earth and mars?
- _Count_ &mdash; numbers are used to keep track: how many times did the car go around the track?

While we can do a lot of things with numbers, there are a few things we can't do with them. For example, say we have the number 20 and the text, "I am 20 years old." While both deal with the idea of 20 as a value, a computer could perform mathematical operations on the first piece of data, but not on the second.