The recycling symbols were generated as a part of a campaign to raise awareness about the environment. It was initiated by an American corporate who has been working in recycled paperboard which sponsored a contest in high schools and colleges to draw the best design for the awareness campaign.
The sign with three arrows going in a triangle indicates that it's recyclable. Sometimes, the sign will come with a percentage sign in the middle, signifying how much of it has been made from recycled materials.
A triangle with three arrows indicates that the item is eligible to be recycled. The numbers and letters act as identification for the recycling teams. Plastics are categorized into one of seven categories, each one a different material that is more or less easy to recycle.