diff --git a/include/uuid.h b/include/uuid.h
index 89b93e6..f5a9412 100644
--- a/include/uuid.h
+++ b/include/uuid.h
@@ -12,6 +12,51 @@
 
 #include <linux/bitops.h>
 
+/*
+ * UUID - Universally Unique IDentifier - 128 bits unique number.
+ *        There are 5 versions and one variant of UUID defined by RFC4122
+ *        specification. A UUID contains a set of fields. The set varies
+ *        depending on the version of the UUID, as shown below:
+ *        - time, MAC address(v1),
+ *        - user ID(v2),
+ *        - MD5 of name or URL(v3),
+ *        - random data(v4),
+ *        - SHA-1 of name or URL(v5),
+ *
+ * Layout of UUID:
+ * timestamp - 60-bit: time_low, time_mid, time_hi_and_version
+ * version   - 4 bit (bit 4 through 7 of the time_hi_and_version)
+ * clock seq - 14 bit: clock_seq_hi_and_reserved, clock_seq_low
+ * variant:  - bit 6 and 7 of clock_seq_hi_and_reserved
+ * node      - 48 bit
+ *
+ * source: https://www.ietf.org/rfc/rfc4122.txt
+ *
+ * UUID binary format (16 bytes):
+ *
+ * 4B-2B-2B-2B-6B (big endian - network byte order)
+ *
+ * UUID string is 36 length of characters (36 bytes):
+ *
+ * 0        9    14   19   24
+ * xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+ *    be     be   be   be       be
+ *
+ * where x is a hexadecimal character. Fields are separated by '-'s.
+ * When converting to a binary UUID, le means the field should be converted
+ * to little endian and be means it should be converted to big endian.
+ *
+ * UUID is also used as GUID (Globally Unique Identifier) with the same binary
+ * format but it differs in string format like below.
+ *
+ * GUID:
+ * 0        9    14   19   24
+ * xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+ *    le     le   le   be       be
+ *
+ * GUID is used e.g. in GPT (GUID Partition Table) as a partiions unique id.
+ */
+
 /* This is structure is in big-endian */
 struct uuid {
 	unsigned int time_low;
@@ -40,20 +85,78 @@
 #define UUID_VARIANT		0x1
 
 int uuid_str_valid(const char *uuid);
+
+/*
+ * uuid_str_to_bin() - convert string UUID or GUID to big endian binary data.
+ *
+ * @param uuid_str - pointer to UUID or GUID string [37B] or GUID shorcut
+ * @param uuid_bin - pointer to allocated array for big endian output [16B]
+ * @str_format     - UUID string format: 0 - UUID; 1 - GUID
+ * Return: 0 if OK, -EINVAL if the string is not a valid UUID
+ */
 int uuid_str_to_bin(const char *uuid_str, unsigned char *uuid_bin,
 		    int str_format);
+
+/*
+ * uuid_bin_to_str() - convert big endian binary data to string UUID or GUID.
+ *
+ * @param uuid_bin:	pointer to binary data of UUID (big endian) [16B]
+ * @param uuid_str:	pointer to allocated array for output string [37B]
+ * @str_format:		bit 0: 0 - UUID; 1 - GUID
+ *			bit 1: 0 - lower case; 2 - upper case
+ */
 void uuid_bin_to_str(const unsigned char *uuid_bin, char *uuid_str,
 		     int str_format);
+
+/*
+ * uuid_guid_get_bin() - this function get GUID bin for string
+ *
+ * @param guid_str - pointer to partition type string
+ * @param guid_bin - pointer to allocated array for big endian output [16B]
+ */
 int uuid_guid_get_bin(const char *guid_str, unsigned char *guid_bin);
+
+/*
+ * uuid_guid_get_str() - this function get string for GUID.
+ *
+ * @param guid_bin - pointer to string with partition type guid [16B]
+ *
+ * Returns NULL if the type GUID is not known.
+ */
 const char *uuid_guid_get_str(const unsigned char *guid_bin);
+
+/*
+ * gen_rand_uuid() - this function generates a random binary UUID version 4.
+ *                   In this version all fields beside 4 bits of version and
+ *                   2 bits of variant are randomly generated.
+ *
+ * @param uuid_bin - pointer to allocated array [16B]. Output is in big endian.
+ */
 void gen_rand_uuid(unsigned char *uuid_bin);
+
+/*
+ * gen_rand_uuid_str() - this function generates UUID v4 (random) in two string
+ *                       formats UUID or GUID.
+ *
+ * @param uuid_str - pointer to allocated array [37B].
+ * @param          - uuid output type: UUID - 0, GUID - 1
+ */
 void gen_rand_uuid_str(char *uuid_str, int str_format);
 
 /**
  * uuid_str_to_le_bin() - Convert string UUID to little endian binary data.
  * @uuid_str:	pointer to UUID string
  * @uuid_bin:	pointer to allocated array for little endian output [16B]
+ *
+ * UUID string is 36 characters (36 bytes):
+ *
+ * xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+ *
+ * where x is a hexadecimal character. Fields are separated by '-'s.
+ * When converting to a little endian binary UUID, the string fields are reversed.
+ *
  * Return:
+ *
  *    uuid_bin filled with little endian UUID data
  *    On success 0 is returned. Otherwise, failure code.
  */