Description: Land administration and cadastral systems in the 21st century depend on the use of information technology (IT) tools. The application of these tools affects very much the systemsТ efficiency and costs. While commercial softwares have helped to establish the infrastructures of today and continue to do so, open-source alternatives, which have achieved considerable significance in many IT fields, have grown to provide credible alternatives for consideration. For various reasons, however, they are not often used in land administration and cadastre, even when their potential is increasingly recognised. This booklet aims to shed light on this potential, exploring the advantages, and disadvantages of open source solutions within the context of cadastre and land registration. The publication is the result of four years of cooperation between FAO and FIG.