My Favorite is Java.
For the people who do not know what or don't know much about other programming languages, if interested:
# What it is: An open-source, interpretive, server-side, cross-platform, HTML scripting language, especially well-suited for Web development as it can be embedded into HTML pages.
# Why you should learn it: Its particularly widely used. "High-speed scripting with caching, augmented with compiled code plug-ins (such as can be done with Perl and PHP) is where the future is. Building Web apps from scratch using C or COBOL is going the way of the dinosaur," said Duquaine.
# Job availabilities: 1,152
# What it is: A general-purpose, compiled, object-oriented programming language developed by Microsoft as part of its .NET initiative, it evolved from C and C++
# Why you should learn it: Its an essential part of the .Net framework. "Learning C#, which is just Java with a different name plate, is critical if you heavily use Microsoft," said Duquaine.
# Job availabilities: 5,111
# Why you should learn it: Ever since Google Maps put AJAX, well, on the map, the requests for AJAX-knowledgeable pros went through the roof. "The demand for AJAX knowledge is huge because its so damned hard to learn," said Huckaby. Of note, Microsoft announced recently plans to release a tool named Atlas that will make AJAX easier to implement. "If Microsofts Atlas tool is successful, it would bring the extreme complexity and annoyance of AJAX to the average worker," said Huckaby.
# Job availabilities : 1,106
# Why you should learn it: Embedded into HTML, its used in millions of Web pages to validate forms, create cookies, detect browsers and improve the design. With its simplicity to learn as well as wide use, its considered a great bang for your educational buck.
# Job availabilities: 4,406
# What it is: Perl is an open-source, cross-platform, server-side interpretive programming language used extensively to process text through CGI programs.
# Why you should learn it: Perls power in processing of piles of text has made it very popular and widely used to write Web server programs for a range of tasks. "Learning some form of scripting language, such as Perl or PHP is critical if you are doing Web apps," said Duquaine.
# Job availabilities: 4,810
# What it is: A standardized, general-purpose programming language, its one of the most pervasive languages and the basis for several others (such as C++).
# Why you should learn it: "Learning C is crucial. Once you learn C, making the jump to Java or C# is fairly easy, because a lot of the syntax is common. Also, a lot of C syntax is used in scripting languages," said Duquaine.
# Job availabilities: 6,164, including all derivatives
7. Ruby and Ruby on Rails
# What they are: Ruby is a dynamic, object-oriented, open-source programming language; Ruby on Rails is an open-source Web application framework written in Ruby that closely follows the MVC (Model-View-Controller) architecture.
# Why you should learn it: With a focus on simplicity, productivity and letting the computers do the work, in a few years, its usage has spread quickly. As a bonus, many find it easy to learn.
# Job availabilities : 210 and 54, respectively
# What it is: An object-oriented programming language developed by James Gosling and colleagues at Sun Microsystems in the early 1990s.
# Why you should learn it: Hailed by many developers as a "beautiful" language, it is central to the non-.Net programming experience. "Learning Java is critical if you are non-Microsoft," said Duquaine.
# Job availabilities: 14,408
# What it is: An interpreted, dynamically object-oriented, open-source programming language that utilizes automatic memory management.
# Why you should learn it: Designed to be a highly readable, minimalist language, many say it has a sense of humor (spam and eggs, rather than foo and bar), Python is used extensively by Google as well as in academia because of its syntactic simplicity.
# Job availabilities: 811
10. VB.Net (Visual Basic .Net)
# What it is: An object-oriented language implemented on Microsofts .Net framework.
# Why you should learn it: Most argue that VB.Net is currently more popular than ever and one of the only "must-learns." "It is currently dominating in adoption and that is where all the work is," said Huckaby.
# Job availabilities: 2,090.
Click on the following link, to see the most popular programming languages, their status, programming of the year, and much more, it is also up-to-date (May 2011):