Microplastics are environmental pollutants that have attracted increasing attention in environmental studies and scientific research due to their widespread presence in various environmental components and the difficulty of removing them once they enter natural systems. They are plastic particles typically smaller than five millimeters. These particles may form when larger plastic waste breaks down under the influence of sunlight, friction, and weathering, or they may be released directly from small sources, such as synthetic fibers generated during laundry and wear particles released from plastic products and vehicle tires. These particles enter rivers, seas, soil, and air through various pathways, including rainwater runoff, wastewater discharge, industrial and agricultural activities, and improper waste disposal. They may travel long distances through water currents and wind, making them pollutants capable of reaching areas far from their original sources. Many types of plastic can persist in the environment for extended periods because they degrade slowly, while continuing to fragment into smaller particles known as nanoplastics, which may be difficult to detect using conventional monitoring methods. Microplastics enter food chains when they are ingested by various organisms, ranging from plankton and crustaceans to fish, birds, and other animals. Their ingestion may create a false sense of fullness without providing nutritional value, cause gastrointestinal irritation, or affect feeding efficiency and growth in some organisms, depending on particle characteristics and the quantity consumed. These particles may be transferred between trophic levels; however, the extent of their transfer and accumulation varies according to the organism’s species, feeding habits, and excretion processes. The biological effects of microplastics depend on several factors, most notably particle size, shape, and chemical composition, as well as the dose, duration of exposure, and type of organism. Their surfaces may carry certain chemical pollutants present in the environment, while plastic products themselves may contain chemical additives used during manufacturing. Nevertheless, the association of pollutants with plastic surfaces does not necessarily mean that these substances will be transferred to living organisms in biologically significant quantities. The extent of such transfer depends on the substance involved, environmental conditions, and interactions occurring within the organism. The effects of microplastics are not limited to aquatic environments; they also extend to soil, where these particles may arrive through irrigation water, sewage sludge used in certain agricultural practices, and the breakdown of plastic waste. They may affect the physical properties of soil, including its structure and the movement of water and air. They may also interact with microorganisms that play essential roles in organic matter decomposition and nutrient cycling. These effects vary according to plastic type, concentration, and soil characteristics, and further research is still needed to understand some of their long-term consequences. In the atmosphere, microplastic particles may be transported with dust and air currents. Some airborne particles may be inhaled, depending on their size, concentration, and duration of exposure. This phenomenon has attracted researchers’ attention to the pathways through which microplastics enter the human body and other living organisms, as well as their potential effects on tissues and biological functions. However, scientific evidence regarding their long-term health risks remains variable, making it important to distinguish between the presence of these particles in the environment and the demonstration of a specific health effect caused by them. Environmental Importance and Pollution-Reduction Measures: Reducing the spread of microplastics requires limiting the use of single-use plastic products, reusing and recycling materials whenever possible, improving waste collection and treatment, and developing wastewater treatment technologies that reduce the release of particles into rivers and seas. Addressing pollution sources, such as synthetic fibers and tire-wear particles, also helps reduce their environmental emissions. Developing accurate methods for detecting microplastics, measuring their concentrations, and monitoring their distribution is essential for understanding their effects and establishing effective environmental policies. In conclusion, microplastics represent a complex environmental challenge associated with human consumption, waste management, and ecosystem sustainability. Studying them is important for identifying their sources, tracing their transport pathways, and assessing their potential effects on living organisms, soil, water, and air. Such research can help raise environmental awareness and develop scientific solutions that contribute to protecting biodiversity and preserving environmental quality for future generations.