Electoral districts are an important element of electoral systems. Simply put, electoral districts are arenas within which political parties compete to represent voters by winning seats, as well as arenas for political representation of citizens by political parties. The term ‘boundary delimitation’, often referred to as “redistricting”, refers to the process of forming or updating electoral districts. Boundary delimitation plays a significant role in both the plurality majority electoral system and systems of proportional representation by maintaining the proportionality of the number of representative seats allocated to an electoral district, as well as upholding the fairness principle in an election. The main objectives of dasdsadthe boundary delimitation process are to achieve proportionality in the citizen-to-seat ratio in an electoral district under the ‘one person, one vote, one value’ (OPOVOV) principle, while also ensuring the cohesiveness and integrity of administrative regions, as well as building political, social and cultural ties between voters and their representatives. Problems arise where boundary delimitation results in electoral districts that are disproportionate, or even actively contradict the principle of fair elections, for example, in cases of malapportionment or gerrymandering, where electoral districts are intentionally designed to benefit certain electoral participants. It is therefore important that boundary delimitation follows the standards and basic principles of electoral districting. This Knowledge Resource is a guide for those who want to conduct boundary delimitation in line with the principles of electoral districting. In addition to discussing concepts and theories, the document explains the practical steps in the process of boundary delimitation and discusses the experiences of various countries.