PLA (Polylactic Acid) is a biodegradable, sustainable and food safe polymer made from organic sources.
It is the most common used filament in FFF 3D printers for its ease of use and wide range of applications, specially those not mechanically or thermally demanding. Definitely a good starting point to learn about the 3D Printing manufacturing process.
Aesthetic, concept models
Investment casting molds
Low mechanically demanding prototypes