Hello World
The classic first program. In Ruby, you use puts to print text with a newline, or print without one. To read user input, use gets. Comments start with #. Semicolons are optional — Ruby doesn't force them on you. Scripts run with ruby filename.rb. There's no main function needed; Ruby executes your code top to bottom.
# Your very first Ruby program
puts "Hello, World!"
# print doesn't add a newline
print "Hello "
print "World!\n"
# Reading input from the user
puts "What is your name?"
name = gets.chomp
puts "Hello, #{name}!"
# Comments start with # — they're ignored by Ruby
# This is a comment
# So is this