SOLID is an acronym that represents five pillars of object-oriented programming and code design theorized by Uncle Bob (A.K.A Robert C. Martin) around the 2000s. All developers should have a clear understanding of these pillars for developing software properly to avoid bad design.

Many programming languages become trendy, enjoy a peak, and sooner or later fall out of favor. Today, people are talking about Ruby's decrease in popularity and even its alleged death. Here's why I think Ruby remains a solid programming language and Ruby on Rails a reliable web application framework. 

For many years, I was a big fan of beautiful code. With Ruby, I was amazed by what I was able to do in one line of code. With Java, I loved that I could stream, map, and then collect! But as time passed, I read about many impressive optimizations, small tricks, and clever algorithms, and I got less and less excited about these discoveries.