Biomaterials are designed to interact with living tissues, and bioactive glasses constitute a subgroup of these materials. One of the most important properties expected of biomaterials is their biocompatibility when they are implanted to natural tissues. Bioactive glasses, in particular, due to their high bioactivity and biocompatibility, can bond to soft and hard tissue by forming a hydroxyapatite (HAp)-like layer at the tissue-implant interface. Therefore, these materials play a significant role in tissue engineering. These fields include tissue surgery, cell studies, and bone repair or regeneration by combining the materials. The clinical use of bioactive glasses, particularly in bone tissue engineering, holds significant promise for future developments. In this context, bioactive glasses are widely determined in this chapter. The types, properties, bioactivity mechanisms, chemical structures, fabrication, and clinical applications of bioactive glasses and glass-ceramics are investigated in detail. A vision for future perspectives and prospective applications is provided.