Rosin pressing is a method of extracting oils from plants, such as cannabis using heat and pressure. The process involves applying heat and pressure to the plant material to extract the oils, which are then collected and can be used for a variety of purposes.   

To start, the plant material is placed in a small, flat container called a "rosin bag" or "parchment paper." This container is then placed between two heated plates, which apply pressure to the plant material. The heat and pressure cause the oils in the plant material to be released, and the oils are collected on the parchment paper or in the rosin bag.   

The process is relatively simple and can be done with a variety of different types of equipment, ranging from small, portable hand-held presses to larger, industrial-scale machines. Rosin pressing has become a popular method of extracting oils from plants because it is a simple, efficient, and solvent-free way to produce high-quality oils.