Azure SQL is a fully managed platform as a service (PaaS) that allows users to run SQL Server workloads in Microsoft's cloud by providing automated management of databases and servers. It supports both relational and non-relational data structures. Azure SQL Database offers single databases for isolated use and elastic pools for sharing resources between databases. It provides different service tiers for various workload types, including general purpose, business critical for high transactions, and hyperscale for large databases. Tools for accessing and managing Azure SQL databases include the Azure Portal, Azure Data Studio, SQL Server Management Studio, and SQL Server Data Tools in Visual Studio.