Measuring language usage

It is very difficult to determine what are the most popular of modern programming languages. Some languages are very popular for particular kinds of applications (e.g., COBOL is still strong in the corporate data center^{[citation needed]}, often on large mainframes, FORTRAN in engineering applications, scripting languages in web development, and C in embedded applications), while some languages are regularly used to write many different kinds of applications. Also many applications use a mix of several languages in their construction and use. New languages are generally designed around the syntax of a previous language with new functionality added (for example C++ adds object-orientedness to C, and Java adds memory management and bytecode to C++).
Methods of measuring programming language popularity include: counting the number of job advertisements that mention the language,^[13] the number of books teaching the language that are sold (this overestimates the importance of newer languages), and estimates of the number of existing lines of code written in the language (this underestimates the number of users of business languages such as COBOL).