Alt text (or alternative text/alternative tags) describes the CONTENT and FUNCTION of images on a web page. This comprises all photographs and graphic elements, including but not limited to icons, graphs, branding elements, and logos.
Electronic screen readers use alt text to describe images for the visually impaired. Alt text should not be a copy-paste of your photo caption. Rather, it must describe the image exactly and concisely. Remember, electronic screen readers will also read the photo caption to the user, so the alt text must include information different from the caption.
Caption: The RMC team competes in one of 11 events during West Point’s annual Sandhurst competition.
Alt text: Three Royal Military College cadets, carrying rifles and heavy back packs, and wearing camouflaged Canadian Armed Forces uniforms and helmets, trek across rugged terrain.
In this case, the alt text can’t just simply state that this is a pie chart. A visually impaired reader must also be able to understand the information the pie chart conveys.
Caption: Departmental spending for 2015-16 by program (dollars)
This pie chart illustrates the Department of National Defence’s spending for Fiscal Year 2015-16, broken down by program.
The percentages allocated to each program, from largest to smallest, are:
- 67%, $12,577,878,081 for Defence Capability Element Production;
- 18%, $3,401,386,557 for Defence Ready Force Element Production;
- 7%, $1,360,079,139 for Defence Combat and Support Operations;
- 3%, $453,694,400 for Defence Services and Contributions to Government;
- 2%, $448,245,658 for Internal Services; and
- 2%, $424,789,408 for Defence Capability Development and Research.