What are the applications of C? Is C language outdated?

C language is (still) widely used for a wide range of applications, and it is definitely not an out-dated language.
Below are some of the fields where C language is predominantly used for software development:

1. Embedded systems
2. Operating systems
3. Compilers and interpreters
4. Media Processing (Audio/Video/Signal processing)
5. Software SDKs
6. Device Drivers
7. Servers (Web/Email FTP etc)

These are only some of the fields where C is predominantly used and there are plethora of other applications including games, multimedia and other desktop applications. But this doesn't necessarily mean that C is applicable for any application. You have to use the right tool for the right project (for example, one wouldn't write an embedded system using PHP, or a web-application in C).