A mastaba is:

http://en.wikipedia.org/wiki/Mastaba

a MASTABA is a type of ancient Egyptian tomb in the form of a flat-roofed, rectangular structure with outward sloping sides that marked the burial site of many prominent Egyptians of the country's ancient period. Mastabas were made of mud-bricks or stone. Previously, the kings started being buried in pyramids as opposed to mastabas. Non-royal use of mastabas continued for more than a thousand years

A mastaba is a type of ancient Egyptian tomb structure that was predominantly used during the Early Dynastic Period and Old Kingdom. The word "mastaba" is derived from the Arabic term "mastabah," meaning "bench."

To understand the concept of a mastaba, let's break it down further:

1. Structure: A mastaba is a rectangular or trapezoidal-shaped structure with sloping sides, resembling a bench or low table. It is typically made of mud bricks or stone and has a flat roof.

2. Purpose: Mastabas were built to serve as tombs for high-ranking officials, nobles, and members of the royal family in ancient Egypt. These structures were meant to safeguard the deceased's body and belongings, as well as provide offerings and a space for family members to visit and honor their ancestors.

3. Features: Most mastabas consist of two main chambers: an upper offering chapel and a lower burial chamber. The offering chapel, located on the roof or near the entrance, was where families placed offerings of food and drinks for the deceased. The burial chamber, situated underground, housed the sarcophagus or burial goods of the individual.

4. Evolution: The mastaba form evolved over time to ultimately give rise to the more elaborate pyramids seen during the Old Kingdom period of ancient Egypt. Pyramids essentially built upon the foundation of mastabas by adding multiple levels or steps, creating the iconic triangular shape.

In conclusion, a mastaba is a type of ancient Egyptian tomb structure that served as a precursor to the grand pyramids. It was rectangular or trapezoidal in shape, built to house the deceased and their belongings, and provided a space for offering rituals and ancestral worship.