1. Java / C# / PHP– Apart from being popular, Java and C# are also the best Object Oriented Programming languages. C# powers most of the enterprise application built on ASP.Net web application framework. Similarly Java too has a good market share in enterprise application and has recently got an edge over C# as it is now used for developing popular Android Apps as well. Despite a lot of issues PHP is still very popular as the server side scripting language as it powers approximately 75% of the server sides scripts on the web. Do you know Facebook’s UI is built on PHP!
2. Python / Ruby– Many modern days web application are built using Python or Ruby language. Ruby on Rails (RoR) web framework has been used to design incredibly good looking web 2.0 apps such as Slideshare, Scribd, Basecamp etc. Similarly Django (Python’s web framework) powers very popular Pinterest, Disqus and Instagram.
3. C++ / C– Old is gold. Which language would you use to build – device drivers, embedded systems, Operating Systems, Browsers or anything that is close to hardware? Linux is written in C. Email client Thunderbird and browser Firefox are written in C++ . MySQL and OS like Windows 95, 98 … Windows XP were developed on C++.
4. SQL– Despite all the hype surrounding NoSQL databases, SQL still has an edge for many practical database use cases. Also, it’ll be required for maintenance of already existing millions of databases built on Oracle, SQL Server or MySQL.