diff --git a/internal/httpserver/handler.go b/internal/httpserver/handler.go
index c0a5860..654e7a8 100644
--- a/internal/httpserver/handler.go
+++ b/internal/httpserver/handler.go
@@ -137,7 +137,7 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Process request type. Here we process only known requests types,
-	// by default request should go to specific application's handler.
+	// all other requests will produce HTTP 400 error.
 	switch rInfo.RequestType {
 	// ToDo: move to constants.
 	case "apps_list":
diff --git a/internal/httpserver/httpserver.go b/internal/httpserver/httpserver.go
index a689aa5..a65319d 100644
--- a/internal/httpserver/httpserver.go
+++ b/internal/httpserver/httpserver.go
@@ -22,6 +22,8 @@ type HTTPServer struct {
 	server   *http.Server
 }
 
+// NewHTTPServer creates HTTP server and executes preliminary initialization
+// (HTTP server structure initialized but it doesn't start).
 func NewHTTPServer(ctx context.Context, cfg *configuration.Config, logger *logger.Logger) (*HTTPServer, chan struct{}) {
 	h := &HTTPServer{
 		config:   cfg,
diff --git a/internal/logger/config.go b/internal/logger/config.go
index 7091b6f..0bdd4d3 100644
--- a/internal/logger/config.go
+++ b/internal/logger/config.go
@@ -2,5 +2,6 @@ package logger
 
 // Config represents logging configuration.
 type Config struct {
+	// Debug is a flag that indicates that we should print out debug output.
 	Debug bool `yaml:"debug"`
 }
diff --git a/internal/models/request_info.go b/internal/models/request_info.go
index 60f796a..aaf526d 100644
--- a/internal/models/request_info.go
+++ b/internal/models/request_info.go
@@ -2,8 +2,14 @@ package models
 
 // RequestInfo is a parsed request information to throw into application's handler.
 type RequestInfo struct {
+	// Application is a name of application. We should ask it's handler for metrics.
 	Application string
-	Metric      string
+	// Metric is a metric name with parameters (e.g. requests{path='/',code=200} will
+	// be "requests/path:\//code:200").
+	Metric string
+	// Request type is a type of request. Currently known: "apps_list", "info", and "metrics".
+	// All other request types will produce HTTP 400 error.
 	RequestType string
-	APIVersion  int
+	// APIVersion is a version of API requested.
+	APIVersion int
 }
diff --git a/internal/storage/memory/memory.go b/internal/storage/memory/memory.go
index 742e453..cd2c814 100644
--- a/internal/storage/memory/memory.go
+++ b/internal/storage/memory/memory.go
@@ -9,16 +9,16 @@ import (
 	"go.dev.pztrn.name/metricator/internal/models"
 )
 
+// ErrMetricNotFound appears if requested metric wasn't found in storage.
 var ErrMetricNotFound = errors.New("metric not found")
 
 // Storage is an in-memory storage.
 type Storage struct {
-	ctx      context.Context
-	doneChan chan struct{}
-	logger   *logger.Logger
-	name     string
-
+	ctx       context.Context
+	doneChan  chan struct{}
+	logger    *logger.Logger
 	data      map[string]models.Metric
+	name      string
 	dataMutex sync.RWMutex
 }