diff --git a/httpr.go b/httpr.go
index 4558075..6a0163f 100644
--- a/httpr.go
+++ b/httpr.go
@@ -124,9 +124,8 @@ outer:
 			if (firstChar == ':' || firstChar == '*') && firstChar == child.endpoint[0] {
 				// Do not allow different param names, because only the first one
 				// is saved, so a param won't be available by a new name.
-				//
-				// I am not the one to judge, but it is a little strange to
-				// expect different types of param in one place.
+				// Therefore, it is good to return an error because in this case
+				// you're doing something wrong.
 				if path[i+1] != child.endpoint {
 					return errors.New("param names " + path[i+1] + " and " + child.endpoint + " are differ")
 				}
@@ -208,15 +207,24 @@ func (rr *Router) ServeStatic(path string, root http.FileSystem) error {
 	})
 }
 
-// subPath contains a root path that is being attached in front of a pattern
-// passed by a Handler() func.
+// subPath attaches a base path in front of a pattern.
+//
+// It is not a sub-router, it just passes a resulted pattern down to
+// a router instance.
 type subPath struct {
 	r    *Router
 	base string
 }
 
-// Sub returns a sub-path with a root path, after that you can shorten patterns.
+// Sub creates a group of handlers with the same base path.
 //
+// How to use:
+//
+//	r := httpr.New()
+//	...
+//	s := r.Sub("/api/v1")
+//	s.Handler(http.MethodGet, "/", func(w, r) {...})
+//	s.Handler(http.MethodGet, "/section", func(w, r) {...})
 func (rr *Router) Sub(base string) *subPath {
 	if base[len(base)-1] == '/' {
 		base = base[:len(base)-1]
@@ -228,13 +236,12 @@ func (rr *Router) Sub(base string) *subPath {
 	}
 }
 
-// Handler attaches root path to a given pattern and pass it to a router.
+// Handler registers a handler for a sub-path.
 func (sp *subPath) Handler(method, pattern string, handler http.HandlerFunc) error {
 	return sp.r.Handler(method, sp.base+pattern, handler)
 }
 
-// Param returns a URL parameter (that is set like `/a/b/:key/d`) with a key
-// or an empty string if no such parameter found.
+// Param returns a URL parameter set with :key, or an empty string if not found.
 func Param(r *http.Request, key string) string {
 	if params := r.Context().Value(ParamsKey).(Params); params != nil {
 		return params[key]