HTML VS PDF

Compared with HTML content, information published in a PDF is harder to find, use and maintain. More importantly, unless created with sufficient care PDFs can often be bad for accessibility and rarely comply with open standards.
Neil Williams, Why GOV.UK content should be published in HTML and not PDF

Le format HTML est donc à préférer au PDF pour des raisons de recherche, d’utilisation et de maintenance, en plus de pouvoir être plus facilement rendu accessible.