That's a way to increase the realism to the reader, if you want to get technical - you leave it [character] vague and you let the reader fill in the blanks with their imagination.
Nicholas SparksThank you for coming into my life and giving me joy, thank you for loving me and receiving my love in return. Thank you for the memories I will cherish forever. But most of all, thank you for showing me that there will come a time when I can eventually let you go.
Nicholas Sparks