Brahms' Lullaby, officially known as Wiegenlied, Op. 49, No. 4, is a popular lullaby that was composed by Johannes Brahms in 1868. It is one of the most well-known lullabies in the world and has been used on numerous occasions to soothe babies to sleep. The melody is simple and gentle, making it the perfect choice for calming and soothing babies. The song has also been adapted for music boxes and baby mobiles, further enhancing its popularity.