NotebookSelection

represents the current selection in the current evaluation notebook in the front end.

NotebookSelection[nb]
represents the current selection associated with the open notebook nb.

You can use Options and SetOptions to read and write options associated with your current selection.

Select some text and then set a font option for it:

Find out the option settings for the selected text:

Select some text and then set a font option for it:

Find out the option settings for the selected text:

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Apply a named style to a selection:

Set an option for selected graphics:

You do not need to use NotebookSelection with most notebook-manipulating functions:

Some options are not applicable to individual cells or cell contents: