Most everyone is familiar with the common names of the pharaohs, and that fact that they are most often seen in the rounded oval of a cartouche. Even thought the cartouche was not used until later dynasties, it is still easy to identify the names of kings in early documents.
Kings have a series of names. The names are very formalized, and take on an almost ritualistic view of how kings were address (kind of the like the litany of names associated with the queen of England. (you know, the whole bit with 'Protector of the Commonwealth, etc.?) On each of the pages for the pharaohs in the Chronology section of this site, I list out the known names of each king following the scheme listed below.
Kings have five formal names (although not all of them were used at first). The full monty wasn't used until the 4th dynasty, and then they tended to get more complex as time went on. Some of the least "egyptian" rulers - the Persian and Macedonian dynasties -- has the longest and most complex egyptian set of king-names.
The first name used is commonly called the Horus Name, because it was contained inside a little figure of a Horus falcon perched on the top of a temple building (or religious standard, depending on who you ask), called a serekh, that is supposed to represent a royal residence or temple seen from the top and front at the same time. (Egyptians have a serious issue with perspective, from an artistic view - things are all out of whack and you'll see the front of someone's eye and the profile of their face. Buildings are the same way, you see the top view and the side view all smooshed together).
Anyway, the Horus name was the hieroglyph used to represent 'he' or 'his' in writing (the third person singular pronoun). It is the oldest royal name, and is used form the first king onward. We do not usually recognize the kings Horus names. For example, the Horus Name of the builder of the Great Pyramid (who we know as Cheops) is Horus Medjedu "Horus, the one who hits"
Nebty Name, or Two Ladies Name
The second name is not inside of a cartouche or serekh, but is topped by the figures of a vulture and a cobra. It is known as the Nebti name, or Two Ladies Name. The vulture represents the goddess Nekhbet, wearer of the White Crown of South. The cobra is the goddess Wadjet, wearer of the Red Crown of the the North. Each of the figures is perched on a basket, which confers the meaning 'Lord' or, in this case, 'Lady'.
These are probably even less well known. The Nebty name of Cheops is Nebty-r-medjed "The one who hits for the Two Ladies" It is often similar to the Horus Name.
Golden Falcon Name
The third name is an odd one, represented by the figure of a falcon perched on the symbol for gold. It may simply be a common epithet when referring to the king, but it wasn't really used in the earliest dynasties. The Golden Horus Name is often very similar, and may be the equivalent of calling someone 'The Strong, The Brave', or some other appellation when referring to them in the third person. Kind of like, 'His Majesty, the king'. We rarely see this name. Cheops' is Bikwy-nub "The two golden falcons"
Throne Name, or Praenomen
The fourth name eventually it replaced the Horus name as the standard reference to the King. This name, also called 'The Throne Name' was used for most formal purposes, and is called the Praenomen in most books.
This is the Nesu-Bit name, King of Upper and Lower Egypt. Literally, this is 'He of the Sedge and the Bee' - hence the symbols of hedge and bee preceding the name. Both the sedge (reed) and the bee were used as titles. Nesu, 'He of the Reed', or King of the South. Bity, 'He of the Bee', or King of the North'. Since the king must be both Nesu and Bity, the two signs are used to top the cartouche of the throne name. The praenomen was usually a reference to some religious belief, and often invoked a god or gods in the name.
The praenomen was normally introduced by 'Lord of the Two Lands' and 'The Good God'. "Ramesses" and "Sneferu" are examples of praenomens.
But, finally, the most common name, the nomen -- the name we are most familiar with in our history books - is the 'Birth Name', quite literally the name the king was born with (although not necessarily, some kings may have changed their birth name to something more prestigious or meaningful when they ascended the throne). This is the personal name of the king.
It is only written in a cartouche when the person becomes a king, and is then usually preceded by 'The Son of Re' to emphasize the fact that the king was a god on earth. In most cases, the praenomen and nomen were used to identify the pharaoh.
Most names could (and did) change during the kings life. This is especially true when major upheavals occurred in the reign of the king and he wanted to emphasize some new, positive aspect of his rule.
Mentuhotep did this several times. For example, his horus name changed from Zematawy "Horus, who feeds the hearts of the Two lands" before the war, to "Horus, the god of the white crown" after the war. Then, when he successfully unified the two part of the country, he changed his name once again, to "Horus who has united the two lands".
The word "Pharaoh"
The Egyptians did not call their ruler 'pharaoh' in the beginning. He was simply king, and the combination of names listed above. They did not refer to 'Pharaoh Sneferu', as we might. The title was actually per-aa, 'Great House', which came to mean king or pharaoh later on.
The king was referred to after death (in mortuary carvings) as the 'Osiris King', and the standard phrases , 'True of Voice' or 'Repeating Life' were added to his name.