# Grand Central Dispatch
# What is Grand central dispatch.
What is Concurrency?
Doing multiple things at the same time.
Taking advantage of number of cores available in multicore CPUs.
Running multiple programs in parallel.
Objectives of Concurrency
- Running program in background without hogging CPU.
Grand central dispatch – dispatch queues allows us to execute arbitrary blocks of code either asynchronously or synchronously All Dispatch Queues are first in – first out All the tasks added to dispatch queue are started in the order they were added to the dispatch queue.