Software developer interview: explain the difference between a process and a thread.

Model answer

Give a crisp definition, a comparison, and a practical implication. A process is an independent program in execution with its own memory space; a thread is the smallest unit of execution that runs inside a process and shares that process's memory with other threads. Explain the consequences of that difference. Because processes have separate memory, they are isolated and safer — a crash in one usually will not take down another — but communication between them is heavier, using inter-process mechanisms. Threads are lightweight and share memory, so they communicate easily and are efficient for parallel work, but that shared memory brings risks like race conditions, requiring synchronisation with locks. Mention context: threads suit tasks within one application that need concurrency, such as handling many requests, while separate processes suit isolation or running independent programs. If you know it, add a line on how your language handles this — for example, the concept of a global interpreter lock in some runtimes. Keep it structured; interviewers are checking that you understand not just the definitions but why the difference matters when you write concurrent code.

This is a guide to structure and approach, not a script to memorise — say it in your own words.

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