A mobile measurement partner (MMP) is software that records which ad brought each new user to an app, and opens the right screen inside the app when someone taps an ad. App makers use it to find out which of their ads, and which ad networks, are worth paying for. It is also called mobile attribution software.
An app maker usually advertises on many ad networks at once. Each network claims credit for every install it can. If five networks each claim the same new user, the app maker would pay five times. So the app maker uses an independent company, the MMP, to decide which ad gets the credit. This work is called attribution.
The MMP does it with deep links. A deep link is a web link that opens a particular screen inside an app, such as a product page, instead of the app's first screen. Each ad carries its own deep link. When a person taps the ad, the MMP records the tap: which ad, which network and what time. If the app is not installed yet, the person goes to the Play Store first. When the app opens for the first time, the MMP matches the new install with the earlier tap. It then opens the screen the ad promised. This is called a deferred deep link.
Say a grocery delivery app in Pune runs ads offering ₹100 off a first order of mangoes. The ads run on three mobile ad networks and through a demand-side platform (DSP). A student taps one of the ads on a news app, installs the grocery app and lands straight on the mango page. The MMP gives the credit to that ad. It applies the usual rule, which gives the install to the last ad tapped within seven days. At the end of the week, the MMP's report shows that one network brought 4,000 installs at ₹45 each. Another network brought 900 installs at ₹130 each, and half of those users never opened the app again. The app maker moves its budget to the first network.
The MMP also catches fraud. Some fake apps on a phone fire a click a moment before an install, to steal the credit. The MMP rejects clicks that arrive too close to the install.
Privacy rules now limit this tracking. On iPhones, an app must ask permission before it follows a user across other apps. Most users refuse. Android is making similar changes. India's DPDP Act also requires consent for using personal data. So MMPs increasingly report totals for groups of users instead of individual paths, and app makers also use marketing mix modelling.