Microfibers are the most common type of microplastic in the environment. During home laundry, microfibers are released in large quantities from the textile industry by means of sewage effluents and/or sludge. Due to its harmful nature for both aquatic and human species, microplastics have triggered growing concern. They contribute not only to the accumulation of plastics in the environment but also, through absorption, to the spread of micropollutants. Microfibers features such as size, shape, and density have a significant impact on the removal rate of microplastics. Studies show that the introduction of microplastics into the environment is largely a result of wastewater treatment plants (WWTPs). Therefore, precise microplastics detection is essential for microplastics control, as is understanding the presence of microplastics and how they affect WWTPs. The current state of detection and characterisation approaches for microfiber in wastewater is thoroughly covered in this chapter. This chapter also discusses the sources of microfibers, transmission pathway of microfibers into environment, and effects of microfibers on aquatic species and human health.