There are a number of features used that require records to be selected, marked. Some examples are printing Sunday School attendance sheets, and printing mailing labels. To select all records in the view click the 
adding a check mark. All of the records will be marked. Each record that is marked will be highlighted blue. To select individual records click on the record while holding down the CTRL key. Be careful you do not release the CTRL key; all the marked records will be unmarked. Groups of records can be marked by first clicking the top record in the group. Then hold down the SHIFT key and click the last record to be marked.
The column with focus will have blue text in the current version.