Polyether ether ketone (PEEK) is a semi-crystalline thermoplastic with high heat and chemical resistance. It has a melting point of 343°C and retains its mechanical properties even at high temperatures. PEEK is manufactured through step growth polymerization and has various applications including in transportation, medical, aerospace, and electronics due to its strength, heat resistance, and processability. The document also summarizes two research articles about the effects of reinforcement type and thermal aging on PEEK composite properties.