EXE files editing
It is possible to edit the EXE files with a hex editor.
Disassembling
Example of disassemblers: IDA, Ghidra.
Types of reverse engineering
Static
Program is not running.
Dynamic
Program is running.
Dissassemblers
IDA
Ghidra
Cutter
ReClass.NET
Assembly code
Debuggers
Program, which sets breakpoints at different steps of program execution