Let's take the example of a contact list, where each entry is a paragraph with the following elements in common:
With the Type Tool cursor positioned in the last name, choose Window > Styles > Character Styles. When the panel opens, hold the Alt key (Windows)/Option key (Mac) and click the Create new style button at the bottom of the panel.
When the New Character Style dialog opens, name the style lastName. Notice the summary of formatting properties in the Style Settings section of the dialog.
Click OK to close the dialog.
Repeat the process and create character styles that capture the formatting of the last name and the phone number exchange (name the styles accordingly).
Now comes the fun part--assembling the paragraph style from the character style components.
Because InDesign captures paragraph properties from the formatting of the text at the cursor location, position the Type Tool cursor in the main phone number text. Choose Window > Styles > Paragraph Styles and, when the panel opens, Alt+Click/Option+Click the Create new paragraph style button at the bottom of the panel. Name the style listing.
Click the Drop Caps and Nested Styles category at the left of the New Paragraph Style dialog to display the nested styles options.
Click the New Nested Style button, then click the drop-down menu to the right of the word None in the first text field. Choose lastName from the list of character styles.
You want the last name and the comma following it to have the same formatting so, ensure that through is selected in the second column of options.
Select the word Words in the third column, and press the comma key on your keyboard to enter the comma as the delimiter.
Click the New Nested Style button again, this time assigning the firstName style and a colon as the delimiter.
Click the New Nested Style button a third and final time and assign the exchange style with a closing parenthesis as the delimiter. (Click OK to complete the style and close the dialog.)
To use the style, select the paragraphs you want to format and click the style name in the Paragraph Styles panel.
Whether it be one paragraph or a thousand, as long as the paragraphs in your document are uniformly structured, nested styles make it possible to apply complex formatting reliably and consistently at the click of a button.