system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do pencil erasers work?
gpt
Pencil erasers work as a very mild abrasive. They used to contain cornstarch, which is abrasive, but not more than paper. They also contain rubber and oil. When you rub the eraser over the pencilmarks, the eraser essentially sands off the layer of graphite, the rubber also gently rubs off and with it, the graphite is carried away. Leaving eraser shavings on the paper.