Many online sites use IPTC data when displaying photos. The Title and Caption data is often prominently displayed with an image on sites like 500px, Flickr and Smugmug. Adding a creative title or a backstory gives your photos another dimension. Also, if you share to many online portfolios or social media sites, you can centralize your metadata and set the Title and Caption just once, in Aperture.

Precursor: Using Aperture's built-in Flickr, Facebook and Smugmug sharing

Aperture natively supports sharing directly to Flickr, Facebook and Smugmug, which use the Version Name of the image instead of the Title. If you share directly from Aperture to these sites, set the Version Name to a descriptive title as well; in fact it's probably a good idea to just copy and paste the name into both fields if you're using these built-in sharing tools.

Setting the Title and Caption

By default, the Title and Caption are listed in the “General” metadata view. In my Aperture library, I created a custom metadata view called “Online Portfolio”. In addition to Title and Caption, it has all the metadata I want applied to an image before sharing online.

Use a custom metadata view to confirm all your desired metadata is set before sharing photos online

A custom metadata view is not necessary to set Title and Caption; it's a personal choice to make it easier to see everything at once, and confirm that I've populated all the appropriate fields. Also if you're sharing from the built-in tools, you may want to include Version Name in your metadata preset. Refer to this tip for more information about creating and customizing metadata views.

There are size limits on the Title and Caption fields. The IPTC specification limits Title to 64 characters and Caption to 2000 characters. For all but the most prolific writers, these size limits are quite reasonable.

Examples

A few examples of how the Title and Caption from Aperture are displayed in online portfolios and social media sites.

500px

500px: Title and Caption are transferred. Keywords are transformed into hashtags.

Flickr

Flickr: Title, Caption and Keywords are transferred

Smugmug

Smugmug: Title, Caption and Keywords are transferred

Squarespace

Squarespace: Title, Caption and Keywords are transferred

Google+

Google+: Only the Caption is included

Facebook

Facebook generally strips metadata from photos when uploaded. I found its behavior differs depending on how you upload the photo. When posting directly to your timeline, the Title and Caption are not displayed. However, when adding a photo to an album, the Title and Caption are displayed. Uploads directly from Aperture include the Version Name as the title and the Caption.

Facebook: Title and Caption are not included in timeline posts

Facebook: Title and Caption are displayed for photos added to an album

My testing confirmed that Facebook does strip all metadata from the image except for the By-line and Copyright strings. This happens irrespective of the upload method.

Other sites

There are many other image sharing sites in the world. The Embedded Metadata Manifesto maintains a good chart of what image metadata is and isn't maintained across a variety of social media sites. 

A Bonus Tip

Although the Caption field is limited to 2000 characters, you can have multiple paragraphs in a Caption, giving you the flexibility to separate thoughts or tell a brief story about an image. My experience has been hit and miss with multi-paragraph Captions across various online sites. For example, Smugmug and Flickr display the separate paragraphs, while Squarespace collapses all the text into a single paragraph. 

Some online sites will display multi-paragraph Captions

I'll use multiple paragraphs in a Caption when it makes sense for the image. I have not seen an online site truncate the caption at a paragraph break.