I am a bit confused about header files. It is necessary to include the <profile.c> header file in order to plot certain types of graphs, such as an MAE graph. However, it isn't necessary to include such headers as <ta.h> in order to access the library of TA indicators. Why is this so? What is different about these header files?

Cheers

Some headers are already included by default. You can find all default headers and definitions inside the include\default.c file.