Hieroglyphs

Egyptian lore states that the hieroglyphs were given to the Egyptians by the divine scribe Thoth who bore the head of an ibis, a bird.
This form of writing was called mdwt ntr by the Egyptians, meaning god's words. A daily sequence would take place as the sun set in the West (burials were on the west bank of the Nile, people lived on the East).

Ra and the souls of those that had died that day would travel by boat through the underworld accompanied by Isis and Nephthys.
The boat was hauled on golden ropes along the River of Death though the twelve regions until it reached the judgement hall of Osiris. The souls disembarked and the boat continued on it's journey.

In the hall with it's ceiling of fire, Anubis then weighed each Ka's heart in front of the throned Osiris.
If the owner had lived a bad life then the crocodile headed Ammut would devour the heart and the spirit would be condemned to the fires for eternity.

After death, a persons immortal spirit (akh) had to travel through the underworld (Duat). The Duat was divided into twelve regions, one for each hour of the night, each with it's own dangers.

The entrance to each was marked by an arch and as the boat entered, the light of the Sun awoke the inhabitants including both demons and souls of the damned.
A gigantic serpent named Apep (Apophis, Greek) also inhabited the entire length of the netherworld and which sought to impede the Sun's passage.
Finally, in the Hall of Osiris, the deceased person's heart (all other vital organs were removed for mummyfication) was weighed against their past life to ascertain if they were worthy to pass into the afterlife. The burial chambers in pyramids were 'decorated' with hieroglyphs detailing spells and prayers to aid the deceased in their journey, dubbed 'pyramid texts' by Egyptologists.
Later these hieroglyphs appeared on the mummies and other items within the chamber. These were known as 'coffin texts'. Finally, when written on papyrus scrolls they took the generic name 'The book of the Dead' (also known as the Book of Gates).
During the 25th dynasty it was standardized. The standardized version had numbered spells and was written in red and black ink on papyrus.
It is helpful to be aware that it consists, in main, of a list of items to accompany the deceased and can therefore be easily translated in part by breaking it down into the inventory of standard items.

A more formal description of the journey and perils faced by the sun and the deceased through the underworld is known as the 'Book of Amduat' he who is in the Duat. It was a collection of divine wisdom reserved for kings and high priests.

In The Book of Gates, the entrance to each of the twelve regions of the netherworld was marked by a gate and guarded by sentries, the Dwellers on the Threshold. The deceased were required to address each by name as the names were themselves the keys to the gates. Armed with enormous knives these human figures had the heads of animals or were combinations of different creatures. Their names included He who lives on or he who dances in blood. They had to be pacified by reciting the appropriate spells and then posed no threat and could could even extend their protection to the dead person. Another breed of supernatural creature were slaughterers who killed the unrighteous on behalf of Osiris. As well as these supernaturals there were also threats from creatures like crocodiles and snakes.

If all the obstacles of the Duat could be negotiated, the deceased would then be judged in the weighing of the heart ritual, depicted in spell 125. The deceased was led by the god Anubis into the presence of Osiris. There the dead person swore he had not committed any sin from a list of 42 sins, reciting a text known as the negative confession. Then the dead person's heart was weighed on a pair of scales against the goddess Mot who embodied truth and justice. Mot was often represented by a ostrich feather, the hieroglyph sign for her name. At this point there was risk that the deceased heart would bear witness owing up to sins committed in life. Spell 33 guarded again this eventuality. If the scales balanced this meant that the deceased had led a good life and they would find their place in the afterlife becoming marku meaning vindicated and taking eternal life in the Field of Reeds. However, if the heart was out of balance with Mot, then another fearsome beast called Ammut the devourer, stood ready eat it and put the dead person's afterlife to an early end. This scene is remarkable not only for it's vividness but as one of the few parts of the book of the dead with any explicit moral content. The judgement of the dead and the negative confession were a representation of the conventional moral code which governed Egyptian society. For every 'I have not' in the negative confession it is possible to read an unexpressed 'thou shalt not', the negative confession is more divine enforcement of everyday morality, with ethical purity being necessary for progress to the afterlife. Today the predominant philosophic approach is perhaps that of dualism, a person consisting of two aspects, a body and a soul.
The Egyptians believed the spirit consisted of three elements. The first, the personality or ba (depicted as a human headed bird) lived in the tomb but was free to move through time and space.
The second, the ka (spirit of life) left the body at death but had to remain close to it and could not leave the tomb (hence mummification).
It also needed sustenance so offerings were depicted or left in the tomb.
Finally was the person's immortality, the akh, which after navigation of the Duat and judgement was free to travel amongst the stars.