“Smart” maps: You might also call them interactive maps, invisible barriers, or intelligent zoning, among other names (none of which get the whole point across). Here’s what this means:

Most mapping-capable robot vacuums now let you draw invisible, software-based barriers throughout your home, using a smartphone app. It can be incredibly convenient and is one of the most compelling reasons to spend extra money on a robot.

Every brand’s mapping system works a bit differently, but most of them have a handful of features in common. One option is to set up do-not-cross lines or no-go zones, which is a great way to keep bots out of areas where they tend to get stuck or make a mess (like around pet food bowls) Another feature lets you divide the map of your home into rooms (or even smaller subdivisions), so that you can command the vacuum to clean, for example, just the kitchen, or the living room and the dining room, without having to manually move the bot or set up physical barriers.

Other distinguishing smart-map features include: app interfaces and sub-menu systems; ease of editing the barriers; whether it can save multiple maps (for multistory homes); whether it needs to start from the dock, or if it can locate itself anywhere; whether cleaning a non-mapped area screws up your saved map; how many runs it takes for the bot to learn the floor plan (laser-based navigators learn it in a single pass, while camera-based bots need multiple passes but arguably map more thoroughly and accurately); and accuracy of the English translation in some of the apps.

The main downside with smart mapping is that, like anything that increases the complexity of a system, this feature adds more opportunities for something to go wrong, and more opportunities to disappoint the owner. Browse the user reviews for any bot with smart maps, and you’ll find stories about the map failing to set up properly, the app being obnoxiously glitchy, or the bot ignoring the barriers or even just getting confused and wasting its time circling the same few areas. Sometimes these problems appear after a bot gets a firmware update. It’s a huge annoyance and letdown when the smart maps don’t work. But in the best bots, smart maps work properly almost all of the time for almost everyone who owns them—let that guide your decision.