Go maps use a hash table implementation with a bucket array, where each bucket holds up to 8 key-value pairs and uses a hash function to determine the bucket index. When a map grows beyond a threshold, it triggers a concurrent rehashing process that gradually moves entries to a new, larger bucket array without blocking the program. This design ensures O(1) average time complexity for lookups, insertions, and deletions while maintaining thread-safety for read operations during resizing.
m := make(map[string]int)
m["key"] = 42 // Hashes "key", finds bucket, inserts pair
val, ok := m["key"] // Hashes "key", finds bucket, returns value