Samach means to rejoice, be glad, or make joyful. It appears about 155 times. It describes joy, gladness, and celebration — especially in response to God's goodness and deliverance.
Joy is a commanded response to God's salvation. 'Rejoice in the LORD always' (Philippians 4:4) echoes the Psalms' constant call to samach. The kingdom brings joy. Celebrations and festivals are times of simchah (joy). Even in suffering, believers can rejoice in hope.