The term metaverse appeared for the first time in a novel published in 1992. Since the early 2000s, researchers have started to use this term to refer to digital technologies for learners to interact with other users with avatars. The term came to prominence in around 2020 due to the rebranding of Facebook. However, there was no consensus on what kind of technologies should belong to the metaverse and how to conceptualise the term. As such, this paper presents an exploratory review for conceptualising the metaverse based on 19 articles from the Web of Science database. This review focuses on the metaverse trend, how researchers in the past and present conceptualizing the term, and key technologies identified in the metaverse world. The findings identify the major types of technologies used in the metaverse studies and offers a sound theoretical foundation in terms of cognitive, social and teacher presence to understand what future potential of these technologies could bring to online learning. Five major types of technologies are identified which could map to four key elements of the metaverse (i.e., immersion, advanced computing, socialisation, decentralisation). At the end, a model is proposed to connect the key elements of the metaverse and its three presences in the community of inquiry that enhance students' learning outcomes in the metaverse learning environment.