Akkadian is an ancient Mesopotamian language used as a lingua franca of the ancient Near East throughout 2nd and 1st millenia BC. The first known evidence of the language dates back to the middle of the 3rd millenium BC, during the 1st millenium BC Akkadian was replaced by Aramaic, but still remained an official language of Babylonian and Assyrian rulers and a lingua franca. After Cyrus the Great conquered Babylon in 529 BC Akkadian was still used e.g. in the Behistun (Bisutun) Inscription, a trilingual inscription of Darius the Great, it's role as an official language, however, was fading (it was replaced by Old Persian as a language of royal inscriptions and by Elamite as a language of administration, the main spoken language was Aramaic). The last known written evidence of the language dates back to the 1st century AD.
Akkadian is a Semitic language with two main dialects - Assyrian (northern dialect) and Babylonian (southern dialect).
Colophon is a specific part of text at the end of a given text inscribed on a clay tablet. There are usualy some (or all) of the following information written in a colophon: the name of the text, the name of the scribe, if it is a copy, than an information that it is a copy, a date, or some other information regarding the tablet or the text.
Cuneiform script was used as a system of writing for several languages including Sumerian, Akkadian and Hittite. Apart from this oldest type of cuneiform script, there are also other types of cuneiform script, used as a writing system of Ugaritic (alphabetical script) and Old Persian. Cuneiform was used on clay tablets by imprinting a stylus (a sort of a "pen"). The imprint was wedge-shaped and these individual wedges were composed into signs, hence the term "cuneiform" (cuneus = Lat. "wedge").
Hittite is an ancient Indo-European language, used in Anatolia from 18th to 13th century BC, i.e. until the demise of the Hittite Empire around 1180 BC. It was also used as a language of international corespondence with both Hittite and Mitanni Empires. It was deciphered by Prof. Bedřich Hrozný in 1915.
Old Assyrian is an evolutionary stage of the Assyrian dialect of Akkadian used in 20th-18th centuries BC in northern Mesopotamia and in Old Assyrian colonies in Anatolia (most of the textual evidence comes from Kültepe, ancient Kanesh). Old Assyrian known form the textual evidence from these colonies is also known as Cappadocian (after Cappadocia). Cappadocian tablets are of particular importance to Czech scholars, since Kanesh, which had been sought for since the end of the 19th century, was discovered by Czech scholar Prof. Bedřich Hrozný in 1925 (deciphered Hittite earlier in 1915). Hrozný also excavated the first ca. 1000 tablets here, around 400 of which he transported to Prague, where they are deposited today (the rest is in Istanbul).
Old Babylonian is an evolutionary stage of the Babylonian dialect of Akkadian, i.e. an Akkadian used in southern Mesopotamia in 20th-16th centuries BC.
Sumerian is a language of unknown origin with no known related language. Textual evidence comes from ancient Mesopotamia, where it was used as a spoken langauge in the 3rd millenium BC. In the early 2nd millenium BC Sumerian was already extinct as a spoken language, but remained used as a language of literature, rite and science (astronomy etc.) for another two thousand years. Much of the textual evidence comes from the Old Babylonian period, literary texts in particular - copies of older tablets, collections of proverbs etc. Many of the Sumerian literary texts were used as scribal excercises thus they where copied many times - many of the texts aren't known to us from the originals, but from their copies dating back to Ur III period (end of the 3rd millenium BC) or Old Babylonian period (20th-16th centuries BC).