diff --git a/Rewritten-docs.md b/Rewritten-docs.md
index d0c6a51..f6a7afb 100644
--- a/Rewritten-docs.md
+++ b/Rewritten-docs.md
@@ -1783,31 +1783,37 @@ Described roles are:
 ## Terminology
 
 **Instance** -- Represents a university, company or some other organization
-unit. Multiple instances can exist in a single ReCodEx installation.
+ unit. Multiple instances can exist in a single ReCodEx installation.
 
 **Group** -- A group of students to which exercises are assigned by a
-supervisor. It should typically correspond with a real world lab group.
+ supervisor. It should typically correspond with a real world lab group.
 
 **User** -- A person that interacts with the system using the web interface (or
-an alternative client).
+ an alternative client).
 
 **Student** -- A user with least privileges who is subscribed to some groups and
-submits solutions to exercise assignments.
+ submits solutions to exercise assignments.
 
 **Supervisor** -- A person responsible for assigning exercises to a group and
-reviewing submissions.
+ reviewing submissions.
 
 **Admin** -- A person responsible for the maintenance of the system and fixing
-problems supervisors cannot solve.
+ problems supervisors cannot solve.
 
-**Exercise** -- An algorithmic problem that can be assigned to a group.
-They can be shared by the teachers using an exercise database in ReCodEx.
+**Exercise** -- An algorithmic problem that can be assigned to a group.  They
+ can be shared by the teachers using an exercise database in ReCodEx.
 
 **Assignment** -- An exercise assigned to a group, possibly with modifications.
 
-**Runtime environment** -- @todo
+**Runtime environment** -- Runtime environment is unique combination of platform
+ (OS) and programming language runtime/compiler in specific version. Runtime
+ environments are managed by the administrators to reflect abilities of whole
+ system.
 
-**Hardware group** -- @todo
+**Hardware group** -- Hardware group is a set of workers with similar hardware.
+ Its purpose is to group workers that are likely to run a program using the same
+ amount of resources. Hardware groups are managed byt the system administrators
+ who have to keep them up-to-date.
 
 ## General basics