System created by Google. Original paper: Bigtable: A Distributed Storage System for Structured Data.
Database that structures organizes organizes data in table. A data item is represented as a row. Data properties are stored in columns, grouped by column family for efficiency. The system is built to handle a very large number of columns, assuming that each data item will use a restricted subset of them and that the resulting table will be sparse. Transactionality is handled at row level. It also supports out of the box timestamping of cell values, the timestamp being either a time based one or a completely arbitrary number. Built from the basic to be distributed.
The paper itself does not spend time on the underlying algorithms and rather focuses on the functionality Bigtable provides.