Trace means to follow something back to where it came from, like following footprints in snow back to whoever made them. When detectives trace a ransom note to its author, they're finding clues that lead them to the source. Scientists might trace a disease outbreak to a contaminated water supply by carefully tracking where each sick person had been.

The word also means to copy something by drawing over it. When you place thin paper over a picture and draw along its lines, you're tracing it. Artists sometimes trace basic shapes to get proportions right before adding their own details.

A trace can also be a tiny amount of something that remains. After you erase a pencil mark, there might still be a faint trace of it on the paper. When police find traces of mud at a crime scene, they're finding small amounts left behind. If someone vanishes without a trace, they've disappeared so completely that nothing remains to show where they went.

The connecting idea is following or finding something small but significant: whether you're tracing your family tree back through generations, tracing a drawing, or finding traces of evidence, you're carefully following details to discover something important.