As the computers penetrate more and more in every aspect of man's life, software defects cause more than just inconvenience and latency. Software solutions are used in bigger solutions, therefore the solution itself has grown explosively in size and complexity. Lack of proper methods and management models result in inefficient products with significant absence of quality, so reliability of the software products goes under doubt. As a young topic, software engineering has evolved in a mutant manner through a few decades. Software Development Models were introduced one after another evolutionarily based on the predecessors' shortcomings and problems faced while employing. The Agile Software development methodologies are categorized as one group of methodologies based iterative and incremental model, were introduced in early 00s in the Agile Manifesto for Software Development. Data analysis in this text, based on the surveys and results of employing these methodologies by practitioners of different fields and team and project size world wide, reveals the agile methodologies' success in time and cost reduction and improvement in quality and productivity. The study also shows that these methodologies' success is not limited to the project size, as some of the cons' assumptions and predictions have outlined.