Sheath forms when plasma interacts with a boundary depending on the charging on the wall. Ions get accelerated towards the boundary and they reach to Bohm speed at the sheath edge. In weakly collisional plasmas the region where the ions get accelerated is called presheath. In this thesis, the sheath and presheath characteristics of dc unmagnetized single species plasma are investigated. Emissive probes, Langmuir probes, Mach probes, laser induced fluorescence methods are used to measure plasma potential profile, ion drift velocities, electron and ion densities and also electron and ion temperatures. The experimental results are compared with the theories and also some theories are modified. The results are important in fusion plasmas, space plasmas, in industrial plasmas and also in understanding the plasma probes.