The invention of Christmas tree lights can be attributed to many individuals and companies over the years. However, one of the earliest recorded instances of Christmas tree lights dates back to the late 1880s, when Thomas Edison was working on inventing a light bulb. Edison's assistant, Edward Johnson, created a string of light bulbs to be used on a Christmas tree. These light bulbs were connected by copper wire and could be lit up by a simple switch. Over time, these lights evolved and became more popular, and companies such as GE and Westinghouse began mass producing them for commercial use.