azw4 .azw4 file extension is a file format developed by Amazon and is used by applications specifically designed for e-readers. It is mainly found on Kindle e-reader devices, a Kindle software is also available for desktops that allows interpretation and reading of azw4 files. It is used to read e-books normally purchased online. The greatest benefit that comes with using azw4 is that text does not have to stay static, so files transferred from a device with a larger screen to one with a smaller screen are adjusted and one does not have to zoom in order to read.
pdb The .pdb filename extension refers to the program database file format authored by Microsoft. The format is used for storing debugging information about executable files and programming libraries or DLL files. The pdb format was designed to ease the debugging process of executables and program modules by decoupling the debugging information from the end of the program or class library itself to allow the integrated debugger and linker to access the pdb files directly. It doing so, the PDB format facilitates the stepping into/out of runtime libraries. The format and its internals remain the proprietary asset of Microsoft.