LSM Trees, or Log-Structured Merge Trees, are a type of data structure used primarily in databases to manage large volumes of write operations efficiently. They work by initially writing data to a memory table, which allows for fast insertions. Once this table reaches a certain size, it is merged with larger, sorted tables on disk, optimizing read performance. This merging process helps maintain a balance between read and write efficiency. LSM Trees are particularly useful in systems that require high write throughput, such as NoSQL databases like Cassandra and LevelDB, making them popular in modern data storage solutions.