Today you will learn the difference between **constants and variables**.

You will see the** difference **between **constants and variables**,** **as you look at the **picture **below. ** **

Before you can use your **constants** and **variables**, you need to **declare** them.

To declare a **variable**, you use the expression **var**.

`var ActualWeather = "Sunny"`

A **constant **is declared through the keyword** let**.

`let UmbrellaColor = "Red"`

### Other types of values

At the moment, we just stored a **String** in a **constant** and **variable**. In the following, you will learn which** other types of values **can be stored.

* Boolean *(Can assume the following values:

**true**or

**false**)

`var Visible = false`

`let TheEarthisasphere = true`

* Integer *(Can just assume

**integers**)

Integers have `min`

and `max`

properties (The **significance** of `min`

and `max`

properties reveal itself, after you read the paragraph about **type annotations**):

`var Currenttemperature = 25`

`let Lastbillingamount = 10`

* Double *(Can assume

**integers**and

**)**

**decimal numbers**

`var Testvalue1 = 2.44`

`let Testvalue2 = 5`

* Float *(Can assume

**integers**and

**decimal numbers**)

`var Testvalue3 = 3`

`let Testvalue4 = 7.86`

**If you have**** t****o calculate with decimal numbers, remember that a Double is more precise than a Float!**

### Type annotations

If you are sure about the kind of values the constant or variable should store, you can use a type annotation:

`var Visible:Bool = true`

`var Text:String = "This is a sample text"`

`var Number:Int = 8`

or `var Number:Int8 = 5`

`var Firstdecimalnumber:Double = 2.1`

`var Seconddecimalnumber:Float = 2.4`