1. INTRODUCTION

In this review I shall accept certain paradigms on the structure of the Universe. Paradigms on the structure of the Universe have evolved considerably during the last hundred years. This process is continuing until the present time, and changes occur quite often, so it is important that we clearly state the present paradigms. I shall use the term ``Universe'' for the real world around us, and the term ``universe'' for a model of the Universe (say Friedmann-universe). Our accepted paradigms are:

• The Universe evolves from an explosive event termed ``Big Bang'', through the inflation, the radiation-domination era to the matter-domination era; probably we live now in the next era where the dominating constituent of the Universe is dark energy.
• The principal force driving the cosmological evolution is gravity.
• Density perturbations grow from small random fluctuations generated during the inflation; perturbations have Gaussian distribution.
• The main constituents of the Universe are: baryonic matter (stars and planets, hot and cold gas, and primordial gas in voids), dark matter, either cold (CDM) or hot (HDM), and dark (vacuum) energy.
• The Universe is flat - the total mean density of all its populations is equal to the critical density.

There exist a number of excellent reviews on the subject ``Large-scale structure of the Universe'', the most recent one with references to earlier work is the talk by Guzzo [29] in the 19<sup>th</sup> Texas Symposium. The term ``Large-scale structure of the Universe'' itself originated in the contemporary meaning as the title of an IAU Symposium [33], where the presence of filamentary distribution of galaxies and clusters with large empty voids between them was first reported. In this review I use the experience collected at Tartu Observatory during the last 25 - 30 years of the study of the Universe. I shall pay attention to cosmographic aspects of the problem, in particular to the geometrical and physical interpretation of descriptive functions. Also I try to show how advances in observational cosmology have changed our theoretical understanding of the formation and evolution of the structure of the Universe.