fixed grammar issues

Author: jovanpop-msft

articles/sql-database/sql-database-service-tiers-dtu.md

@@ -65,7 +65,7 @@ Performance levels are expressed in terms of Database Transaction Units (DTUs) f
 
 ## DTU Benchmark
 
-Physical characteristics (CPU, memory, IO) associated to each DTU measure are callibrated using a benchmart that simulates real-world database workload.
+Physical characteristics (CPU, memory, IO) associated to each DTU measure are calibrated using a benchmark that simulates real-world database workload.
 
 ### Correlating benchmark results to real world database performance
 It is important to understand that all benchmarks are representative and indicative only. The transaction rates achieved with the benchmark application will not be the same as those that might be achieved with other applications. The benchmark comprises a collection of different transaction types run against a schema containing a range of tables and data types. While the benchmark exercises the same basic operations that are common to all OLTP workloads, it does not represent any specific class of database or application. The goal of the benchmark is to provide a reasonable guide to the relative performance of a database that might be expected when scaling up or down between performance levels. In reality, databases are of different sizes and complexity, encounter different mixes of workloads, and will respond in different ways. For example, an IO-intensive application may hit IO thresholds sooner, or a CPU-intensive application may hit CPU limits sooner. There is no guarantee that any particular database will scale in the same way as the benchmark under increasing load.