Noble titles: Count
In the late Roman Empire, the Latin title comes meaning (imperial) 'companion' denoted the high rank of various courtiers and provincial officials, either military or administrative: before Anthemius was made emperor in the West in 467, he was military comes charged with strengthening defenses on the Danube frontier[1].
Military counts in the Late Empire and the Germanic successor kingdoms were often appointed by a dux and later by a king. From the start the count was in charge, not of a roving warband, but settled in a locality, a countship, his main rival for power being the bishop, whose diocese was often coterminous.
In many Germanic and Frankish kingdoms in the early Middle Ages, the count might also be a count palatine, whose authority derived directly from the royal household, the "palace" in its original sense of the seat of power and administration. This other kind of count had vague antecedents in Late Antiquity too: the father of Cassiodorus held positions of trust with Theodoric, as comes rerum privatarum, in charge of the imperial lands, then of comes sacrarum largitionum (concerned with the strictly monetary fiscal matters of the realm) [1],
The position of comes was originally not hereditary. By holding large estates, many counts were able to make it a hereditary title—though not always. For instance, in Piast Poland, the position of komes was not hereditary, resembling the early Merovingian institution. The title had disappeared by the era of the Polish-Lithuanian Commonwealth, and the office replaced with other institutions. Only after the Partitions of Poland did the title of "count" re-surface in the German-derived title hrabia.
* The title of Count was also often conferred by the monarch as an honorific title for special services rendered, without an actual feudal estate (countship, county), just a title, with or without a domain name attached to it. In the UK, the equivalent Earl is often a courtesy title for the eldest son of a duke. In the United Kingdom stringent rules apply, often a future heir has a lower ranking courtesy title; in Italy, by contrast, all the sons of certain counts are counts (contini). In Sweden there is a distinction between counts (Swedish: greve) introduced before 1809 and after. All children in countship families introduced before 1809 are called count/countess. In families introduced after 1809 only the head of the family is called count, the rest had a status similar to barons and was called Mr. and Ms./Mrs. (before the use of titles was abolished).