Detailed Answer: 

The Button module is an exactly that: an object that you insert into your layout that resembles a physical button.

Uses of this module

• Traditionally, a web button is a pretty package for a link that sends visitors elsewhere when clicked.
  
• The button can also open a lightbox, which displays a video or any other content that you can insert with a shortcode, HTML, or code such as an iframe.

Button examples

Button style

Default button style

If you’re using the Buzz Builder Theme, the buttons’ initial style comes from the settings at Customize > General > Buttons. The button’s default text color is white text for darker accent colors and black text for lighter colors. The default font family for the button text depends on the font family set for the body tag.

Click Action: Link or Lightbox

You can set the button’s click action to either a link or a lightbox.

Set the click action to a link

When you set Click action to Link, a Link section opens.

• Enter the URL to the link or click Select to choose a page or post from your site.
• Set Link target to determine whether the linked page replaces your current page in the same tab ( Same window ) or opens in a new tab ( New window ).
• The Link No Follow field tells search engines whether or not to follow the link. The default is No, which tells search engines to follow the link. Yes means “Yes don’t follow the link.” For more information about when to use nofollow, see the Google webmaster article.

Set the click action to a lightbox

If you choose the Lightbox option, you next choose whether the lightbox will display custom HTML content or play a video from a URL you provide, as described in the following sections.

HTML content

With the HTML option, an HTML editing box lets you enter custom code such as HTML markup, embed code for a video, or shortcode. In the following screenshot, the shortcode for a saved row containing a Call to Action module was inserted into the HTML box to make an opt-in popup.

Other shortcode examples:

• Embed an audio player with audio shortcode.
• Use shortcode from a plugin to display the contents of a PDF file

Video link

Insert the URL of the video you want to play in the lightbox, from a service such as Youtube or Vimeo:

Button settings

General tab

This tab has the following settings.

• Text
  The text that appears on the button.
• Icon
  Optional icon to appear on the button. If you select an icon, there are two additional fields:
  Icon position: Before or after the button text.
  Icon visibility: The icon can be always visible or appear on hover only.
• Click action
  Link or Lightbox.
  If you choose Link, a Link field opens for you to enter a typical URL link to another page or location.
  If you choose Lightbox, a Content type option lets you choose either HTML or Video.
  For HTML, add any code to display in the lightbox.
  For Video, a field opens so you can provide a URL for a video from a service such as Youtube or Vimeo.

Style tab

The Style tab is shown in the screenshot and described below.

1 Top section

• Width
  Auto width: Width adjusts to fit the text and icon.
  Full width: The width expands to the content area minus the module’s margin settings.
  Custom:
  You can set a custom width in px, vw, or %.
• Align (responsive)
  See this article for a description of how the alignment toggle settings work.
• Padding (responsive)
  Set a specific padding value in pixels. Click the Link icon to automatically make all four padding values the same.

2 Text section

• Text color
  Set the button text color in the resting state.
• Text hover color
  Set the button color on hover. If this setting is left blank, the Text color setting applies for hover also.
• Typography section
  See this article about the Typography section settings.

3 Background section

• Background color
  Set the fill color for the button in the resting state.
• Background hover color
  Set the button’s fill color on hover. If this setting is left blank, the Background color setting applies to hover also.
• Background style
  Flat: consistent fill color
  Gradient: gradient of the background color, lighter on top and darker on the bottom.
• Background animation
  Disabled by default. If set to Enabled, there’s a 0.2-second linear transition from resting state to hover state.

4 Border section

See this article for more information about the settings in the Border section.

Advanced tab

There are all the usual Advanced tab settings for margins, visibility, animations, and advanced HTML settings.

Related modules

Other modules that include a button:

• Button Group module
  This module lets you add a group of buttons in a single column. horizontally or vertically.
• Callout module
  This module includes a heading, optional text, optional image (photo or icon), and optional button or link text. The link you provide works with any part of the Callout module, not just the button.
• Call to Action module
  This module includes a heading, optional text, and a button. The link you provide works with any part of the Call to Action module, not just the button.
• Contact Form module
  Special settings to set up a contact form, with a button to submit the form.
• Subscribe Form module
  Special settings to set up a connection to any of a number of mail service providers, creating a form to subscribe with a button to submit the form.