A thread is a lightweight unit of a process that can execute independently and concurrently with other threads in the same process. A process can contain multiple threads, and each thread can execute a different part of the program code simultaneously, allowing for better utilization of system resources.
Threads share the same memory space and resources of the process they belong to, but each thread has its own stack to hold its state and local variables. This allows threads to operate independently of each other while sharing the same resources.
Threads can be used to perform multiple tasks simultaneously within a single process, such as processing input/output, responding to user input, and performing background tasks while the main thread handles user interaction. Multi-threading can also be used to improve performance in systems with multiple processors or cores, as each thread can be scheduled to run on a different processor or core.
Threads can be created and managed in many programming languages, including Java, C++, Python, and many others. However, writing multithreaded code requires careful consideration of synchronization and communication between threads to avoid issues such as race conditions, deadlocks, and livelocks.