You can define a single-quoted String escaped by a backslash:
a_string_with_a_quote = 'She said I\'m not going!'
You can put characters like tabs and newlines in a double-quoted string
double_quoted_string = "This is a tab: \t, and this a newline: \n"
You can use placeholders for expressions
author = 'Antoine de Saint-Exupéry'
title = 'The Little Prince'
puts "#{author} wrote #{title}"
Ruby offers a way to avoid backslash
string = %q{"Yeehaw" the cowboy yelled, I'm not going!}
Ruby can span lines
string = "one line
two lines
three lines"
Now that you have an string definition you can use some methods to manipulate it.
# Gets string size
string.length
# Concatenates other_str to str
str + other_str
# Tests str and obj for equality
str == obj
# Returns true if str is empty
str.empty?
# Returns a copy of str with all occurrences of pattern replaced
str.gsub(pattern, replacement)
# Returns the index of the first occurrence of the given substring
str.index(substring [, offset])
# Returns a collection with strings delimited by ','
collection = "One, Two, Three".split(',')