Most people come to egypt to see the Pyramids and ancient monuments, so it's worthwhile knowing at least a bit about the styles of architecture and teh different buildings.
Early kings and nobles were buried in these block-like, above-ground tombs, intially of mudbrick and then of stone. They contain many storerooms and were usually built over a deep burial shaft to protect the dead person.
There are still many theories about the building of the pyramids and their function -- were they temples? Tombs? solar observatories? The consensus is that they were tombs, burial chambers for the pharaoh on a scale we have never seen since.
The gradual development of the 'true pyramid' can be easily seen from the earliest mastabas to the step pyramid, then the pyramid at Maidum, the bent pyramid, red pyramid, and finally the great pyramids at giza. Built of stone and rubble cores, most pyramids were sheathed in smooth limestone and -- according to some, at least -- were painted brilliant white and decorated with painted hieroglyphs.
And, even though we see the pyramids as standing alone, they were always built as part of a larger pyramid complex which included a valley temple and a mortuary temple and causeway. See Pyramids.
Part of the mortuary complexes for the pharaohs included temples -- mortuary and valley, and often Sun temples that follow a very specific blueprint. Nearly every temple we saw was of the three-part variety: courtyard, hypostyle hall, sanctuary and it becomes easy to figure out the ruins onc eyou know how the basic layout is done.
Some believe that obelisks are precusors to pyramids, or at least represent the idealizied pyramid, which in turn represent the rising of the original land from the the primeval seas.
Some tombs, notably those in Aswan or Beni Hassan, are simple chambers cut into the stone of the cliffs near the Nile -- normally on the West bank, towards the setting sun (although by necessity some are on the east bank when cliffs are not available. Other tombs, like those in the Valley of the Kings, are long, deep corridors into the stone. More on this in Tomb Architecture.