1. Process vs Thread

Process — a program in execution, with its own isolated memory space, resources, and state. Each process gets its own code, data, heap, and stack; its own file descriptors, registers, and PC; and isolation from other processes (one crash doesn't crash others).

Thread — a unit of execution within a process — lightweight, shares the parent process's memory. Each thread has its own stack + registers + PC, but shares the heap, code segment, global data, and file descriptors with its sibling threads.

Aspect Process Thread
Memory	Separate address space	Shared address space
Creation cost	Heavy (fork/exec)	Light
Communication	IPC (pipes, sockets, shared mem)	Direct (shared memory)
Isolation	Strong — crash is contained	Weak — one bad thread can kill all
Context switch	Expensive	Cheap
Example	Chrome tabs (separate processes)	Chrome's JS engine threads

Why it matters: processes give you isolation (browser tabs, microservices); threads give you parallelism with shared data (web server handling requests, a game engine's physics + rendering).

Analogy: a process is a factory — its own building, equipment, workers. A thread is a worker inside that factory — workers share the floor and tools but each does their own task.

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