diff --git a/README.md b/README.md
index 48c4989..4b9d5d3 100644
--- a/README.md
+++ b/README.md
@@ -243,7 +243,7 @@ But most importantly:
 
 ### Simulation iteration evaluation algorithm
 
-- __MT__: main thread, controls the flow, HIGHEST PRIORITY
+- __MT__: manager/main thread, controls the flow, HIGHEST PRIORITY
 - __WT__: worker thread, evaluates a simulation iteration for one or more structures
 - __AT__: applier threads, applies actions and writes the `new stored signal` into the `current stored signal`
   for all blocks
@@ -275,3 +275,35 @@ It's probably not as fast as it gets, but it should be decent
        so that the process can be easily accomplished in multithreading execution environments.
 
 __Note:__ the bigger a machine, the slower it reacts to inputs because signals need more time to travel through the body
+
+### Structs, traits and methods
+
+- world (class), keeps all information about a world
+- structure (trait)
+    - compute(), computes an iteration of the simulation for this structure
+    - get_blocks(), returns an immutable reference to the blocks
+    - clean(), used to clear event queue, also calls clean() on blocks
+- runnable (trait)
+    - run(), does stuff, mostly in another thread
+- manager (impls runnable), manages a world
+- worker (impls runnable), operates a list of creatures in a world
+- applier (impls runnable), operates on a list of creatures in a world, also calls clean() on structures
+- block (trait)
+    - get_connections(), returns an immutable reference to the connection vector
+    - get_value(), returns an immuatable reference to the current stored signal
+    - get_name(), returns an immutable reference to the block's name
+    - compute(), computes an iteration of the simulation for this block, then stores it in the new stored signal.
+      also returns a list of actions that the block wants to perform
+    - clean(), clears event queue and writes new stored signal into the current stored signal
+- action (trait)
+    - get_source(), get the source structure (immutable ref)
+    - get_target(), get the target (immutable ref)
+    - apply(), applies the action
+
+PROBLEM: apply() requires a mutable reference to the target, but it's not possible to pass it in any way. Only an
+immutable ref can be passed.
+
+SOLUTION: use an immutable reference and call as_mut on it?
+
+TODO: figure out where to put UI logic. We probably can't do it in parallel with the simulation, so it needs
+      to be executed by the manager thread.