diff --git a/ntnu/21v/ttk4145/summary/summary.md b/ntnu/21v/ttk4145/summary/summary.md
index 4d6f699..79b2e86 100644
--- a/ntnu/21v/ttk4145/summary/summary.md
+++ b/ntnu/21v/ttk4145/summary/summary.md
@@ -507,3 +507,34 @@ t1(){                           t2(){
 * ... any other interface
 
 
+#### Some standard problems/pit-falls
+
+* **Race condition**: A bug that surfaces by unfortunate timing or order of events
+* **Deadlock:** system in circular wait
+  * Special case of livelock
+  * Does not use CPU
+* **Livelock:** system locked in a subset of states 
+  * like deadlock, but we use CPU
+  * Busy-Waiting is a livelock
+* **Starvation:** A thread does "by accident" not get the necessary resources
+
+
+#### Features in syncronization
+
+* Critical Section - Code that must not be interupted
+* Mutual Exclusion - More piecesof code that must not interrupt each other
+* Bounded buffer - Buffer with full/empty synchronization
+* Read/Write Locks
+  * Readers can interleave eachother
+  * Writers have mutual exclusion
+* Condition Syncronization - Blocking on event or status
+  * Guards etc.
+* Resource allocation
+  * More than mutual exclution!
+  * Ref: The lock manager
+* Rendezvouz/barriere - Synchronization point
+  * Ref: AA "end boundary"
+* Communication
+* Broadcast
+* ...
+