diff --git a/pkg/captcha/captcha.go b/pkg/captcha/captcha.go
index 52ddbd2..17ddc61 100644
--- a/pkg/captcha/captcha.go
+++ b/pkg/captcha/captcha.go
@@ -18,25 +18,24 @@ func NewIntAnswer() Answer {
 	return (Answer(ans.String()))
 }
 
-// Captcha interface that should be implemented by captcha.
+// Captcha interface that should be implemented by a CAPTCHA.
 type Captcha interface {
-	// Image generates and returns an image of captcha.
+	// Image generates and returns a pointer to an image of CAPTCHA.
 	Image(style string) *image.Image
-	// GetAnswer returns a pregenerated answer.
+	// Answer returns a pregenerated answer.
 	Answer() Answer
 	// Solve compares a stored answer with a passed one.
-	// Sets field Solved to true if they are equal.
 	Solve(answer Answer) bool
-	// IsSolved returns field IsSolved.
+	// IsSolved returns if a CAPTCHA is solved or not.
 	IsSolved() bool
-	// Expiry returns a date after what captcha will expire.
+	// Expiry returns a date after what CAPTCHA will expire.
 	Expiry() time.Time
 }
 
 // BaseCaptcha is a base implementation of a CAPTCHA.
 //
-// All derivatives that embed this struct only need to
-// implement Image() method.
+// All derivatives that embed this struct only need to implement
+// an Image() method.
 type BaseCaptcha struct {
 	answer   Answer
 	solved   bool
@@ -53,6 +52,8 @@ func (c *BaseCaptcha) Image(style string) *image.Image {
 	return nil
 }
 
+// Answer generates an integer answer for a CAPTCHA or just returns
+// an existing one.
 func (c *BaseCaptcha) Answer() Answer {
 	if c.answer == "" {
 		c.answer = NewIntAnswer()
@@ -60,6 +61,8 @@ func (c *BaseCaptcha) Answer() Answer {
 	return c.answer
 }
 
+// Solve sets solved field to true if given answer is right and returns a result
+// of a check.
 func (c *BaseCaptcha) Solve(answer Answer) bool {
 	c.solved = c.answer == answer
 	return c.solved
@@ -73,6 +76,8 @@ func (c *BaseCaptcha) Expiry() time.Time {
 	return c.expireIn
 }
 
+// ExpiryDate returns a date when CAPTCHA expires. It adds a passed
+// expiry duration to a current time.
 func ExpiryDate(expiry time.Duration) time.Time {
 	return time.Now().Add(expiry)
 }