There are fifty-one alphabets starting from a-kāra (a-kara) to kṣa (ksha)—

a-kārādi-kṣa-kārāntaikapañcāśad varṅāḥ. 

The Bṛhaspati (Brihaspati) smṛti (smriti) text says that the Creator churned the series of alphabets out of a machine—

dhātrākṣarāṇi sṛṣṭāṇi yantrārūḍhānyataḥ purā.

These alphabets are of five types, namely lithograph, artistic scripts, scripts written by pen, scripts produced by colour dust, and swirl-born scripts.

mudrālipiḥ śilpalipi-rlipilekhanīsambhavā,

guṇḍikā ghūrṇasambhūtā lipayaḥ pañcadhā smṛtaḥ. 

• There is a remarkable tale about the origin of alphabets, with which the Supreme Architect Brahmā (Brahma) is associated. It has been chronicled that at the end of the universal cataclysm, when the world was flooded with water, Prajāpati (Prajapati) Brahmā, concerned about creation, was despondent and anxious. The moment he became distressed, a youth appeared and stood before him, chanting from Vedas. The four-headed Brahmā assumed  this chant that was bereft of sound, could not be touched, was odourless and tasteless. He then entered a meditative state, and started wondering about who this man was, who had presented himself before him in the guise of a young man. His contemplation resulted in the generation of akṣara (akshara) (here, letters) that had no expression, tactile sensation, or form, devoid of smell or flavour. Brahmā, in his meditative state, saw that the alphabets, resembling celestial forms, were white, black, blood-red and yellow. They were non-females and non-eunuchs. Thus, Brahmā, realising the true nature of akṣara, once more re-assumed his contemplation. Then, the only heavily voiced white syllable emerged from the vocal cords of a ruminative Brahmā. It was this syllable that was Veda, Omkāra (Omkara) or Śiva (Shiva) himself — sa omkāro bhavedvedaḥ akṣaraṃ vai maheśvaraḥ. When Brahmā deliberated on akṣara again, Ṛgveda (Rigveda), Yajurveda (Yajurveda) and the trisyllabic omkāra developed one after the other. After this, fourteen syllables composed of various letters emanated from the four faces.

According to this purāṇa (purana), these sixty-three letters have their origin in a-kāra (a-kara) which is the first vowel—tasmāt triṣaṣtivarṇā vai akāra-prabhavāh smṛtaḥ. It is said that the fourteen Manus born from the fourteen letters. Finally, Vāyupurāṇa (Vayupurana) has said, “Manus assume the position of, and live on as, vowels and letters across epochs [as in kalpa]. Since vowels manifest as letters, all letters have a relation with vowels.

As described in Bhāgavatapurāṇa (Bhagavatapurana), it was from omkāra that Brahmā created the approximants and the lateral (ya, ra, la, va), the fricatives (śa, ṣa, sa, ha), the vowels (a to au), the plosives (ka to ma), and the group of letters distinguished by their short and long sounds—

tato’kṣara-samāmnāyam asṛjad bhagavānajaḥ;

antaḥsthoṣma-svara-sparśa-hrasva-dīrghādilakṣaṇam.