The stress carried by the solid particles or the solid portion of the soil is known as effective stress.
Pore water pressure:
The stress carried by the pore water is known as pore water pressure.
The compressive stress at a point which may or may not consists of geostatic stresses and induced stresses, is carried partially by the solid portion of the soil and partially by the pore water. Geotechnical engineers call this stress total stress because it is the sum of stresses carried by these two portion of the soil i.e solid portion and pore water.
Karl Terzaghi was the first to introduce the importance of effective stress and since then it is one of the major concepts is soil mechanics.