Every type in ruby is a class, so they use CamelCase

String

"Hello World"

Integer

1

Float

3.14

TrueClass

# there is no Boolean type
# true and false are different type

true

FalseClass

false

Array

# You can put any type of value inside of it

[1, "Hello", 3.14, false, true] 

Sets

# It's like import or include in other language
require "set"

Set.new [1, 2, 3]

Hash

{:foo => 1}

# Or

{"foo": 1}

# Or

{foo: 1}

# Also you can 

{1 => 2, list: [], true => false}