Marty Carroll, Director of Usability Practice, The
Usability Company
Below is a list of key issues and considerations for usability
and accessibility that are applicable to all websites.
Images and Animations:
Accessibility: Alt tags - the descriptive text attached to
graphics, which allows screen-readers to articulate them - should
accompany every image, even blank spaces comprised by gifs.
Animations should be kept to a minimum and should include an
option to switch them off
Usability: Alt tags help those without sight problems because they
provide useful information about the images that may not be clear
from their appearance. In addition, for those on slower Internet
connections, alt tags provide information on downloading images
allowing the user to decide whether they want to wait for the
download or not
Image Maps:
Accessibility: If an image is a link then it should have alt
tags, which say what the image links to
Usability: It does not suffice to simply have a description of the
image in the alt tag if the image is a link. The alt tag should
always provide information on where it is linking to in the same
way as a text link
Multimedia:
Accessibility: A website should provide captioning and
transcripts of audio material and descriptions of video
Usability: While much has been made of multimedia, many Internet
users in the UK do not have the bandwidth to support multimedia.
Alternative presentation of multimedia (such as text) should
always be provided to accommodate these users and for those whose
environment (busy office, quiet train coach, etc) precludes their
use of multimedia
Hypertext Links:
Accessibility: Use text that makes sense when read out of
context. For example, avoid repetitive use of "click
here" and "more"
Usability: Use words that describe the feature or the function of
the destination page because this allows users to make informed
decisions on whether they wish to use the links. Research shows
that people often scan a page for links rather than reading all of
the text available so descriptive links are paramount
Page Organization:
Accessibility: Where possible, use style sheets to keep content
data separate from the data governing that content's presentation
Usability: Style sheets allow for consistency in the presentation
of information and consistency is the hallmark of usability. Good
use of style sheets mean that people learn to use sites
effectively much more quickly
Graphs and Charts: Accessibility: Use 'Longdesc tags' with
graphs and charts because these tags provide in-depth textual
descriptions of contents
Usability: The provision of 'Longdesc tags' can help with
communicating the meaning of complicated graphs and charts. Using
'Longdesc tags' to convey this information can save valuable
screen space
Scripts, Applets, and Plug-ins:
Accessibility: Provide alternative content in case active
features are inaccessible or unsupported
Usability: The security setting on a user's PC or the presence of
a company firewall often means that features may be unavailable to
a large part of the population. Many of the new Internet users
feel intimidated using the Internet and will not install plug-ins
on their PC's
Frames:
Accessibility: Provide a "no frames" option and if
frames are used; make sure the titles attached to them are
meaningful
Usability: The use of frames means that it is difficult to
bookmark pages of a site. If someone wants to send a web address
to a friend via email for reference purposes then copying the URL
from the browser will not work if frames are used because the URL
refers to the frameset rather than the page the user is viewing
Tables:
Accessibility: Rows and columns need to relate to one another
so that information in each cell can be understood in context
Usability: N/A
Check your work:
Accessibility: Look out for simple spelling mistakes and check
that the accessibility elements added meet W3C's guidelines at http://www.w3.org/TR/WCAG
Usability: Of course, the presence of simple spelling mistakes
conveys the impression that the site is shoddy and will
consequently lead to a lack of trust. Conformance to accessibility
guidelines does not necessarily equate to good accessibility - how
people with various disabilities actually use the site needs to be
taken into account. For example, while software may indicate that
alt tags are present these alt tags may not be very useful
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