The advantage of using Rails is its agility; it makes developing your web applications easy and fast. The disadvantage is that it can leave holes in your security if you are not aware of common vulnerabilities. It's a nerve-wracking and unfortunate fact that there are plenty of malicious people lurking on the Web. As a Rails developer, it is essential that you understand how to assess risk and protect your data and your users. 
Security on Rails uses established security principles to teach you how to write more secure software, defend your applications from common threats, and encrypt your data. We'll give you an example of a hacking exploit, and explore how to fix the weaknesses in an application.

You'll learn the steps you need to take to control access to information and authenticate users, including cryptography concepts and authorization. In addition, you'll see how to integrate your applications with external management systems; in short, the crucial details you must consider to protect yourself and your data.

The most important element of security is to plan for it before it becomes an issue. Security on Rails helps beginner and intermediate developers to take control of their applications and guard against attacks.