Hittite and other, generally older texts were written using cuneiform script, which was formed by pressing a wedge-shaped stylus into moist clay. Hittite scribes borrowed the cuneiform script from Syria, where it was being used to write the East Semitic language Akkadian. Cuneiform had been invented in ancient Sumeria, over a thousand years earlier, and numerous other cultures had borrowed cuneiform, like the Hittites adapting it to their particular needs.
Because cuneiform script was a combination of syllabic (syllable-sign) and logographic (word-sign) characters, modern transliteration conventions have been adopted in order to distinguish what was syllabic from what was logographic. Upper- and lower-case Latin letters and italics "transliterate" these distinctions. Transliteration, then, uses Latin letters for cuneiform signs depending on the type of use:
While cuneiform signs for Sumerian words ("Sumerograms") and Akkadian words ("Akkadograms") would appear in Hittite text, Hittite scribes reading & writing those signs would pronounce appropriate Hittite words in place of the Sumerian or Akkadian words. In a sense, then, Hittite scribes had to be trilingual and would perform translation on-the-fly while reading & writing Hittite text. This form of writing was not for ordinary people! And, of course, not all Hittite scribes were equally gifted. Modern transliteration conventions have been adopted in order to mimic cuneiform practice, allowing its study in detail while simultaneously allowing use of the more-convenient Latin script: keyboards and displays (or pens and paper) instead of styli and wet clay. Transliteration, then, represents text in its written form; hyphens are used to segment syllabic sequences that were written with multiple cuneiform signs, so that each sign is implicitly revealed.
Transcription, on the other hand, is a modern means of representing text (here, Hittite) in its spoken form. In the case of Hittite, transcription is intended to reveal the language as an ordinary individual would have heard & spoken it in ancient times. In our example texts, Hittite may be transliterated before being transcribed, then glossed and translated. (N.B. Our distinction of 'transliteration' vs. 'transcription' is not uniformly rigid; e.g., we distinguish these terms while presenting our example texts, here, but not always so clearly for example in our EIEOL lesson series Hittite Online where our use of the term 'transcription' may be more loose, including perhaps what we here call transliteration. As a rule of thumb, the presence of [many] hyphens in "Hittite text" signals 'transliteration' of cuneiform script while their [rarity or] absence signals 'transcription' of the Hittite language.)
Despite the fact that scribes borrowed Sumerian/Akkadian cuneiform to write the Hittite language, Hittite was actually a quite different language from those others; hence, cuneiform could at best only approximate Hittite pronunciation, sometimes poorly. (Latin letters may be no better, despite the fact that they are more familiar to us.) Furthermore, even when proper distinctions could be made in cuneiform, Hittite scribes did not necessarily make them! For example, Hittites normally ignored a cuneiform symbol for 'b' + vowel and used, instead, a cuneiform symbol for 'p' + vowel, no matter whether the Hittite word being written contained a 'b' or a 'p' sound before the vowel. Again, scribes had to figure things out on-the-fly. So must modern transcribers, for example substituting a 'b' where a transliterator may have [accurately] rendered a 'p'. And, of course, a transcriber may write a Hittite word where a transliterator records a Sumerian or Akkadian word.
Not all complications in reading Hittite are mentioned here, but one more is worth noting. Where they appear, acute accents denote the secondary syllable value (1st alternate reading), grave accents denote the tertiary value (2nd alternate reading), and numerical subscripts (4 and up) denote yet other values. So, for example, plain 'u' denotes the first value (most common reading) of the syllable containing the vowel U, 'ú' denotes the second value, 'ù' denotes the third, subscript '4' denotes the fourth, etc. However, there is no full agreement among scholars concerning the need for or significance of marks signalling readings, so these may or may not be observed in transliteration or transcription.