Facebook is updating its data use policy in an attempt to give people more clarity on how the company uses information they share. As part of the changes, Facebook also is signaling that it may start showing people ads on sites other than Facebook, targeting the pitches to interests and hobbies that users express on Facebook. The move comes a week before Facebook Inc.’s expected initial public offering of stock. The policy changes are in response to an audit by Irish data-protection authorities last year, Facebook said Friday. Facebook plans to notify its more than 900 million users of the changes through advertisements around the site and on its mobile apps. Users who want to dig deeper can read a version of the policy that highlights the changes word by word. Erin Egan, Facebook’s chief privacy officer, will host an online chat Monday to answer any questions. Egan said the company wasn’t substantially changing its business practices, but wants to “err on the side of providing too much information.” As part of the changes to the policy, Facebook has created a section to explain how it uses technologies such as cookies to deliver ads, secure the site and offer various features. Cookies, which are small files containing data or alphanumeric IDs, are commonly used to track people’s activities around the Web, for example. The information could then be used to target ads to their hobbies and interests. The changes also incorporate updates that Facebook has made to its site since its previous policy revision announced in September. This includes reorganizing people’s profile pages in a “timeline” format and adding an “activity log” that lets people see everything they’ve done on the site, as well as who can see it. Facebook also has given itself more leeway on how long it keeps information it collects. Before, it has typically kept such data for 180 days. Facebook said it will now retain data for “as long as it is necessary to provide services.” This could be longer or shorter than 180 days.