As technological developments expand the communicative and participatory potential of more individuals, showcasing how legitimacy manifests and is debated and explored in diverse online platforms and settings remains a fertile area of future research. Bottom-up participation is therefore a fundamental concept, one made even more significant when framed within online possibilities, and notably one that draws close links to the public sphere. The diversification of online modes of participation in the public sphere continues, and this can be “theorized as increasing the availability or participatory politics for civic actors, who employ these tools to exert voice and influence in the public sphere”. Although discourse analysis, generally speaking, has existed as a powerful approach to the analysis of spoken and written discourse for a considerable period of time, what has changed is the type and diversity of texts that form the basis of discursive interactions and engagement. The chapter also presents an overview of the key concepts discussed in this book.