Fused filament fabrication (FFF) is one of the most widely adopted additive manufacturing (AM) technologies, valued for its affordability, simplicity, and adaptability to a wide range of thermoplastic materials. This chapter provides a comprehensive overview of the FFF 3D printing process, focusing on its operational principles, material options, and the key parameters that influence the final quality of printed parts. In the FFF process, thermoplastic filaments are extruded layer by layer to create objects with complex geometries, high customization, and minimal material waste. The performance of printed parts, such as surface finish, dimensional accuracy, mechanical strength, and structural integrity, is highly dependent on process parameters, which are categorized into slicing settings, build orientation, and temperature conditions. Each of these categories includes several subparameters that can be fine-tuned to achieve the desired output. Additionally, this chapter explores the wide-ranging applications of FFF across sectors such as biomedical engineering, aerospace, architecture, electronics, and consumer products. Emphasis is placed on the role of material innovations and advanced process control in expanding the potential of FFF from rapid prototyping to functional part manufacturing. Through this detailed review, the chapter highlights the growing significance of FFF in modern digital manufacturing ecosystems.
