Here are some popular and highly-rated books on Ruby:
<ol>
<li>"The Ruby Programming Language" by David Flanagan and Yukihiro Matsumoto: This book is considered the definitive reference on Ruby, and provides a thorough and comprehensive overview of the language, its syntax, and its features.
</li>
<li>"Programming Ruby: The Pragmatic Programmer's Guide" by Dave Thomas and Andy Hunt: This book is a classic guide to Ruby, and provides a practical and hands-on introduction to the language and its core concepts.
</li>
<li>"Eloquent Ruby" by Russ Olsen: This book is a guide to writing elegant and idiomatic Ruby code, and provides detailed examples and practical tips on how to write clean, maintainable, and efficient Ruby code.
</li>
<li>"The Well-Grounded Rubyist" by David A. Black: This book is a comprehensive and practical guide to Ruby, and covers advanced topics such as metaprogramming, testing, and performance optimization.
</li>
<li>"Practical Object-Oriented Design in Ruby" by Sandi Metz: This book is a guide to object-oriented design in Ruby, and provides practical advice and examples on how to apply OO principles and patterns to Ruby code.
</li>
</ol>

Here are some popular and highly-rated books on Ruby:

1.  "The Ruby Programming Language" by David Flanagan and Yukihiro Matsumoto: This book is considered the definitive reference on Ruby, and provides a thorough and comprehensive overview of the language, its syntax, and its features.
    
2.  "Programming Ruby: The Pragmatic Programmer's Guide" by Dave Thomas and Andy Hunt: This book is a classic guide to Ruby, and provides a practical and hands-on introduction to the language and its core concepts.
    
3.  "Eloquent Ruby" by Russ Olsen: This book is a guide to writing elegant and idiomatic Ruby code, and provides detailed examples and practical tips on how to write clean, maintainable, and efficient Ruby code.
    
4.  "The Well-Grounded Rubyist" by David A. Black: This book is a comprehensive and practical guide to Ruby, and covers advanced topics such as metaprogramming, testing, and performance optimization.
    
5.  "Practical Object-Oriented Design in Ruby" by Sandi Metz: This book is a guide to object-oriented design in Ruby, and provides practical advice and examples on how to apply OO principles and patterns to Ruby code.

Best Ruby books