After weeks and months of shutting businesses and schools, communities in the United States and around the world are talking about what it will take to open up again. One tool is “contact tracing,” a practice whereby health workers find those who have been exposed to a disease, such as COVID-19, in order to stop its spread. But COVID-19 presents some unique challenges for tracing. People without symptoms can spread it and for some, it can be deadly. Apple and Google among other tech entities are offering help that will allow people to learn, through the use of apps on their smartphones, whether they have been exposed to the coronavirus. VOA explains how that might work. VOA Khmer's Chenda Hong narrates in Khmer.