The plastic industry has shown pronounced growth in the last decades. In fact, world plastic production increased from 1.5 to 390.7 million tons from 1950 to 2021. The expansion of this industry has been boosted by plastics' low density, durability, excellent barrier properties and relatively low cost, making them ideal materials for extensive commercial, industrial, medicinal and municipal applications. Even though their robustness was initially celebrated, their long lifetimes make them persistent and difficult to degrade. Due to increased convenience and single-use-habits in large parts of the world most plastics produced have a short useful life and get discarded frequently. Therefore, they enter the environment at high rates that are not matched neither by the rates of natural removal processes nor cleanup actions, leading to accumulation in the environment. Plastic pollution can be reversible when physically removed, but it can become poorly reversible when weathering processes induce the fragmentation of plastic items into micro-and nano-plastic particles. Even though the definition of micro-and nano-plastics has been a subject of debate, plastic fragments with a size ranging from 1 µm to 5 mm are generally defined as microplastics, while those with smaller sizes than 1 µm are listed as nanoplastics. Micro-and nano-plastics' small size and low weight promotes their transportation and settlement in different environments. As of today, they have been found in marine, and terrestrial systems, as well as in the atmosphere. The concept of a 'microplastic cycle' was introduced to understand better plastic pollution and the fluxes that connect the transport and transformation of microplastic across different compartments of the ecosystem with drastic consequences for many species. In this regard, reducing the introduction of microplastics into the marine environment will limit their transport into other ecosystems, which will require governmental and societal changes, connected with increased awareness.