Twitter is updating its mobile apps to start tracking which apps people download and which ones they use and how often. The company says the data, which it will begin collecting following an update to its apps for Android and iPhone users, will help it better tailor its ads to users.

Google and Apple also have data about which apps users download from their respective marketplaces. is starting to get a piece of it as well with its Appstore. A number of startup companies also try to track smartphone owners’ app usage, like Appcelerator, Lotame and Apptopia. Android and iOS both allow third parties to collect app usage data.

Twitter said it will notify users from within the app before collecting any data, but will likely upset some users and privacy advocates by making the new method of harvesting user data opt-out, meaning it will collect app usage information unless users ask it to stop.

Twitter knows which accounts its users follow, and scans their tweets to look for information that might help it make more money on advertising. The company already uses targeted advertising -- or ads that are selected based on user information that’s also collected by companies like Facebook and Google -- to sell ads at a higher price. However, compared to rival social network Facebook, Twitter has only a fraction of possible information about its users.

Facebook collects similar data from apps that use software that allows users to sign in with their Facebook credentials and skip signing up for a username and password. Apps like Spotify and Candy Crush notably use Facebook sign-ins.

Twitter uses an algorithm to determine which tweets to recommend. It will also use the new data to improve its “recommended tweets,” or those shown to its users from accounts they do not follow.