diff --git a/src/gui/profilergraph.h b/src/gui/profilergraph.h
index 6354ac9ef..186304468 100644
--- a/src/gui/profilergraph.h
+++ b/src/gui/profilergraph.h
@@ -30,11 +30,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 class ProfilerGraph
 {
 private:
+	// One-frame slice of graph values.
 	struct Piece
 	{
 		Piece(Profiler::GraphValues v) : values(std::move(v)) {}
 		Profiler::GraphValues values;
 	};
+	// Data for drawing a one graph. Updates every frame.
 	struct Meta
 	{
 		float min;
@@ -54,6 +56,8 @@ class ProfilerGraph
 
 	ProfilerGraph() = default;
 
+	// Adds graph values to the end of graph (rendered at right side) and
+	// removes the oldest ones (beyond the `m_log_max_size`).
 	void put(const Profiler::GraphValues &values);
 
 	void draw(s32 x_left, s32 y_bottom, video::IVideoDriver *driver,
diff --git a/src/profiler.h b/src/profiler.h
index e7135d9c2..3e28b8e24 100644
--- a/src/profiler.h
+++ b/src/profiler.h
@@ -29,21 +29,55 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/timetaker.h"
 #include "util/numeric.h"      // paging()
 
-// Global profiler
 class Profiler;
+// Global profiler. Its data is available for user.
 extern Profiler *g_profiler;
 
 /*
 	Time profiler
-*/
 
+	Collects data (time intervals and other) in two independent cycles.
+
+	- Cycle for profiler graph lasts for one frame and managed in 
+	`Game::updateProfilerGraphs()`, result is displayed by `ProfilerGraph`.
+
+	- Cycle for all other data lasts for `profiler_print_interval` seconds (user
+	setting) and managed in `Game::updateProfilers()`, result is given in text
+	form by `print` function. User can view it via in-game profiler menu or
+	"/profiler" command.
+
+	All data is cleared at cycle end.
+*/
 class Profiler
 {
 public:
 	Profiler();
 
+	/*
+		Adds value to given profiler entry (`name`). Does not change count
+		in the entry.
+
+		As a resut, profiler will give *sum* of record values as value and "1" as avgCount.
+		(If only this method is used for given entry between profiler updates)
+	*/
 	void add(const std::string &name, float value);
+
+	/*
+		Adds value to given profiler entry (`name`) and increases its record count
+		by 1.
+	
+		As a resut, profiler will give *average* of record vaues as value and count of
+		records as avgCount.
+		(If only this method is used for given entry between profiler updates)
+	*/
 	void avg(const std::string &name, float value);
+	/*
+		Sets value to given profiler entry (`name`) if it is larger then existing one and
+		increases record coutn by 1.
+
+		As a resut, profiler will give *max* record value as value and count of records as avgCount.
+		(If only this method is used for given entry between profiler updates)
+	*/
 	void max(const std::string &name, float value);
 	void clear();
 
@@ -55,6 +89,7 @@ class Profiler
 
 	// Returns the line count
 	int print(std::ostream &o, u32 page = 1, u32 pagecount = 1);
+	// Writes values on page into `o`.
 	void getPage(GraphValues &o, u32 page, u32 pagecount);
 
 
@@ -87,7 +122,10 @@ class Profiler
 
 private:
 	struct DataPair {
+		// Recorded value. Recording method depends on used functions (add/avg/max)
+		// of profiler
 		float value = 0;
+		// Count of records.
 		int avgcount = 0;
 
 		inline void reset() {
@@ -102,33 +140,53 @@ class Profiler
 	};
 
 	std::mutex m_mutex;
+	// All the profiler entries, stored untill `clear()` call.
 	std::map<std::string, DataPair> m_data;
+	// Values for profiler graph collected untill next frame draw. Value history
+	// are stored in `ProfilerGraph`.
 	std::map<std::string, float> m_graphvalues;
 	u64 m_start_time;
 };
 
+
 enum ScopeProfilerType : u8
 {
+	// Accumulate measurements untill profiler update.
+	// Profiler will print sum as value and "1" as count.
 	SPT_ADD = 1,
+	// Accumulate measurements and record count untill profiler update.
+	// Profiler will print average value as value and record count as count.
 	SPT_AVG,
+	// Accumulate measurements until frame update and then add sum to profiler graph.
 	SPT_GRAPH_ADD,
+	// Save only the largest recorded value. Profiler will print them as value and "1" as count.
 	SPT_MAX
 };
 
-// Note: this class should be kept lightweight.
+/*
+	A class for time measurements. Each created object records time from its
+	construction till scope end.
 
+	Note: this class should be kept lightweight.
+*/
 class ScopeProfiler
 {
 public:
+	/* 
+		Begins record untill scope end. Result will be added to `name` profiling
+		entry in `profiler` (profiling entries are created/deleted automatically).
+	*/
 	ScopeProfiler(Profiler *profiler, const std::string &name,
 			ScopeProfilerType type = SPT_ADD,
 			TimePrecision precision = PRECISION_MILLI);
+
+	// Ends record and logs result in profiler.
 	~ScopeProfiler();
 
 private:
 	Profiler *m_profiler = nullptr;
 	std::string m_name;
-	u64 m_time1;
+	u64 m_time1;  // Record start time
 	ScopeProfilerType m_type;
 	TimePrecision m_precision;
 };