I present the essential results of my doctoral thesis, which wasdone in the field of lattice QCD. This work can be seen as one of thecornerstones of a long-ranging project, started already at the beginning of theyear 2000. Since then, several groups, associated in the Bern-Graz-Regensburg(BGR) collaboration, continuously worked on that project.In this report I will discuss results on various sectors of lattice QCD. There,seven sets of gauge field configurations with a lattice size of 16x32and a spatial extent of about 2.2 fm have been created; the pion masses areranging from 602 MeV down to 257 MeV. The configurations include two massdegenerate dynamical light quarks; the Lüscher-Weisz gauge action and theChirally Improved Dirac operator have been used. In each set 200 or 300uncorrelated configurations are available for analyses.The results are located in three different fields. An analysis of low energyparameters was done, to be more precise, the axial Ward-identity mass and (thepion and kaon) decay constants have been investigated. The experimentallyaccessible value for the ratio of these decay constants is in full agreementwith the value obtained here. The second area of research was concerning theangular momentum decomposition of the vector meson rho. In our approach itcould be shown that the first excited state of the rho meson is not a pureS wave state, which is contrary to the quark model. The main focus of thiswork was based on hadron spectroscopy. This task was done using the variationalmethod. A broad spectrum of baryons and mesons could be covered here. Alsohadrons including strange quarks have been analyzed, however, the strange quarkbeing a partially quenched strange quark. Generally speaking, the studied hadronchannels compare nicely to the experimental values.