A process is a program being executed. A process includes a PC Program Counter which indicates where the next instruction is, access permissions (based on UID and GID), and memory (both data memory and text memory).
A process is not simply a string of instructions as that definition could equally well apply to the image of the binary which is stored on disk).
A process is always in exactly one of a few states: running, waiting for the CPU, waiting for I/O,