What can be?Versión en línea What goes around the world but stays in a corner? por Manuel Licerán Sánchez 1 Most of them are squares. Hints 1 They can be in different colours. 2 Now a day, they are hardly used. 3 Many people collect them. 4 They are sticked on envelopes. 5 If you open the envelope with this on it, you can take and read the letter.