What is the difference between asynchronous and parallelism?

Asynchrony is the ability to perform tasks without waiting for the completion of previous ones. A task is initiated, and control is returned to the caller immediately. The result will be received later via a callback, Future, or another mechanism.

Parallelism is the simultaneous execution of multiple tasks. This is achieved by utilizing multiple processor cores.

Key differences:

Feature	Asynchrony	Parallelism
Goal	Optimize resource usage during I/O operations, reduce blocking of the main thread.	Speed up computations by using multiple computing units.
Execution	Tasks can run in a single thread, switching between them while waiting.	Tasks are executed simultaneously on different cores/processors.
Requirements	Does not require multi-core processors for basic implementation.	Requires multiple computing units (cores).
Example	Downloading a file from the network while keeping the user interface responsive.	Processing a large data array by dividing it into parts and computing each part on different cores.

Asynchrony and parallelism do not exclude each other and are often used together to achieve maximum performance and responsiveness. For example, an asynchronous operation can be performed in parallel with other tasks.