OLE DB (pronounced as separate letters) is a set of COM-based interfaces that expose data from a variety of sources, such as spreadsheets, project plans, SQL, legacy databases and more. OLE DB interfaces provide applications with uniform access to data stored in diverse information sources, or data stores. These interfaces support the amount of database management system (DBMS) functionality appropriate to the data store, enabling it to share its data.
In it’s very simplest terms, it means what (mathematical or logical) operator is more important than others. This is a very important concept, without rules as to which instruction to do first, computers would be pretty stupid. Take the example of