Let me summarize the takeaway points that you learned in this section:

• Multiple threads can work together by signaling each other using a conditional variable
• A conditional variable requires the waiting thread to acquire a mutex before it can wait for a conditional signal
• Every conditional variable requires unique_lock that accepts a mutex
• The unique_lock<std::mutex> method works exactly as lock_guard<std::mutex> with some additional useful functionalities, such as deferred locking, manual lock/unlock, ownership transfer, and so on
• Unique_lock helps avoid deadlocks just like lock_guard, as the mutex wrapped by unique_lock gets unlocked automatically when the unique_lock instance goes out of scope
• You learned how to write a multithreaded application that involves threads that signal each other for synchronization