Dynamic languages are one of the most interesting fields in programming, because it gives the developer more functionality & flexibility in developing applications.
The reasons of this are
The ability to modify the code in runtime, which saves the time of compiling, linking and building the application.You can imagine editing the code that runs on a robot walking on Mars from earth, this actually happened in NASA using LISP, and imagine how difficult this can be if you were using compiled languages.
Usually the dynamic language codes are less complicated than static language codes.
Usually dynamic languages support both Object Oriented and Functional Oriented models of programming.
Portability level is always higher in interpreted languages
Dynamic language syntax is usually easier and shorter if compared with equivalent codes in other compiled language