diff --git a/src/TNL/File.h b/src/TNL/File.h
index 8e0836b359cf54f559c9cc274d61f7ff39a4de27..b690d610c10fa6f9c242d65679f959f08de9fcf0 100644
--- a/src/TNL/File.h
+++ b/src/TNL/File.h
@@ -88,7 +88,7 @@ class File
       return this->writtenElements;
    }
 
-   /// \brief Function that gets elements from given file.
+   /// \brief Method that can write particular data type from given file into GPU. (Function that gets particular elements from given file.)
    ///
    /// Returns boolean value based on the succes in reading elements from given file.
    /// \param buffer Pointer in memory.
@@ -101,7 +101,7 @@ class File
    template< typename Type, typename Device = Devices::Host >
    bool read( Type* buffer );
 
-   /// \brief Function that writes elements into given file.
+   /// \brief Method that can write particular data type from CPU into given file. (Function that writes particular elements into given file.)
    ///
    /// Returns boolean value based on the succes in writing elements into given file.
    /// \param buffer Pointer in memory.
diff --git a/src/TNL/Logger.h b/src/TNL/Logger.h
index 5b7fda238a90468ad4aedd984eb55b40d3dd7077..c6e672d4fd863830a27652eebfdb67d613e2f73b 100644
--- a/src/TNL/Logger.h
+++ b/src/TNL/Logger.h
@@ -19,16 +19,29 @@ class Logger
 {
    public:
 
+   /// \brief Basic constructor.
+   ///
+   /// \param _width Integer that defines the width of logger.
+   /// \param _stream Where to create the logger, e.g. cout or a certain file.s
    Logger( int _width,
               std::ostream& _stream );
 
+   /// \brief Creates header in given logger.
+   ///
+   /// \param title String desribing the title/header.
    void writeHeader( const String& title );
 
+   /// \brief Creates predefined separator - structure in the logger.
    void writeSeparator();
 
+   /// \brief Inserts information about system parameters into logger.
+   ///
+   /// \param parameters
    bool writeSystemInformation( const Config::ParameterContainer& parameters );
- 
 
+   /// \brief Inserts a line with current time into logger.
+   ///
+   /// \param label Description of the current time line.
    void writeCurrentTime( const char* label );
 
    // TODO: add units
diff --git a/src/TNL/Timer.h b/src/TNL/Timer.h
index 8bf31c192ba997d0fe47c15e4e03e304796e614e..3d40bc485a4cc84ce999598498d8b1e24d354dec 100644
--- a/src/TNL/Timer.h
+++ b/src/TNL/Timer.h
@@ -53,7 +53,7 @@ class Timer
       /// It returns the elapsed time between calling the start() and stop() functions.
       /// Starts counting the real time after the function start() is called and
       /// pauses when the function stop() is called.
-      /// If the timer have been started more then one time without resetting,
+      /// If the timer have been started more then once without resetting,
       /// the real time is counted by adding all intervals (between start and stop
       /// functions) together.
       /// This function can be called while the timer is running, there is no
@@ -70,7 +70,7 @@ class Timer
       /// Returns the number of CPU cycles (machine cycles).
       unsigned long long int getCPUCycles() const;
 
-      /// \brief Writes a record to the \e logger.
+      /// \brief Writes a record into the \e logger.
       ///
       /// \param logger
       /// \param logLevel A whole number from zero up, which indicates the indent.
@@ -96,7 +96,7 @@ class Timer
  
    unsigned long long int initialCPUCycles, totalCPUCycles;
 
-   /// \brief Saves information about state of the timer.
+   /// \brief Saves information about the state of given timer.
    ///
    /// Knows whether the timer is currently stopped or not.
    bool stopState;