Explain the concept of a stream in programming and its main characteristics.

A thread in programming is a sequence of execution of commands within a process. Threads allow multiple tasks to be performed simultaneously by sharing the process resources.

Main characteristics of a thread:

• Independence of execution: each thread executes independently but can interact with other threads.
• Shared address space: threads of the same process share memory and resources, which facilitates data exchange but requires synchronization.
• Execution context: each thread has its own call stack, registers, and state.
• Parallelism: on multi-core processors, threads can run simultaneously, increasing performance.

In C/C++, threads can be created using libraries such as std::thread (starting from C++11).