As multi-faceted institutions, borders have a bearing on continental integration in Africa. This is because they have an influence on who and what moves from one country to another. In this sense, any discussion of continental integration in Africa brings borders to the centre stage, because, while integration assumes the free flow of the factors of production, including people, borders sift and select who or what has the freedom of passage or not. This selectivity of African borders is antithetical to the goals and aspirations of the 1991 Abuja Treaty Establishing the African Economic Community (hereafter, the Abuja Treaty). The same is true for Agenda 2063, the African Union’s (AU) strategic framework designed to socio-economically transform Africa over the next half century. Automatic beneficiaries of the selective impact of borders are the so-called state actors and formal institutions and enterprises, which assume legal personhood; while their counterparts, the informal actors including informal cross-border traders, must always negotiate the border. T his brings to the fore the nature, logic and operationalisation of regional and continental integration in Africa. In this context, we are led to ask whether the informal actors and people at the grassroots, such as cross-border traders, are an objective reality at African borders, as well as to reflect on their role and actual or potential efficacy in the continental integration project. First, however, there is a need to define and clarify the concepts that drive the papers in this special issue of Africa Insight. These concepts are borders, the informal economy and informal activities, and regional integration. Borders are not just lines at the margins of nation-states, but also social and political institutions. This means that, beyond playing the ordinary role of managing migration and immigration, borders perform social and political functions that may not always be located at the physical border. The articles in this special issue tease out various and nuanced understandings of the term ‘border’ in relation to Africa and the journey towards regional integration. Samuel Ojo Oloruntoba, for instance, perceives the border as an arbitrary and artificial site of economic flows, which is essentially political, social, spatial and economic in construction. Flows are indeed evident at the border, as it marks the limits of national territory and controls the movement of people and flow of goods. For Inocent Moyo, the border is multifaceted, consisting of many and dynamic practices. Christopher Nshimbi picks up on this dynamic feature of the border, and adds to it the interrelations of inclusion and exclusion or inside/outside relations. This brings the conception full circle – from the border being a site of economic or human flow, to its marking of the limits of national territory. By logical extension, we then come back to borders not only being a site of flow, representing openness, but also a site of control of flow or movement, representing closure.