The Wayback Machine - https://web.archive.org/web/20150822200532/https://dev.twitter.com/cards/types/summary

Summary Card

The Summary Card can be used for many kinds of web content, from blog posts and news articles, to products and restaurants. It is designed to give the reader a preview of the content before clicking through to your website.

The Tweet below shows a Summary Card (photo and text) below the 140 characters:

Our system recognizes when URLs are included in a tweet, and crawls your site to fetch the Card type and content. To learn more about how our Card system works, read our Getting Started Guide.

Sample Code

Adding a Summary Card to your tweets is as simple as adding the below meta tags to your site:

<meta name="twitter:card" content="summary" />
<meta name="twitter:site" content="@flickr" />
<meta name="twitter:title" content="Small Island Developing States Photo Submission" />
<meta name="twitter:description" content="View the album on Flickr." />
<meta name="twitter:image" content="https://farm6.staticflickr.com/5510/14338202952_93595258ff_z.jpg" />

Be sure to provide your own site attribution and content.

Once the tags are live, you can test your Card using our Twitter Card Validator.

Reference

Below are the suggested minimum properties for the Summary Card including title, description, and image.

Card PropertyRequired

twitter:card

Should be set to a value of “summary”		Yes

twitter:site

The Twitter @username the card should be attributed to. Required for Twitter Card analytics.

Yes

twitter:title

Title should be concise and will be truncated at 70 characters.		Yes

twitter:description

A description that concisely summarizes the content of the page, as appropriate for presentation within a Tweet. Do not re-use the title text as the description, or use this field to describe the general services provided by the website. Description text will be truncated at the word to 200 characters.		Yes

twitter:image

URL to a unique image representing the content of the page. Do not use a generic image such as your website logo, author photo, or other image that spans multiple pages. The image must be a minimum size of 120px by 120px and must be less than 1MB in file size. For an expanded tweet and its detail page, the image will be cropped to a 4:3 aspect ratio and resized to be displayed at 120px by 90px. The image will also be cropped and resized to 120px by 120px for use in embedded tweets.		No

For a full list of supported tags, please see the Cards Markup Tag Reference.

Mappings from Deprecated Product Card

On July 3, Product Cards will be deprecated and map to Summary Cards. All required fields of the product card directly map to the Summary Card. Label and Data properties will be ignored.