Atlas of Worlds
The Atlas of Worlds replaced the existing map system as part of the Atlas of Worlds expansion, released on September 2, 2016. The Atlas is a series of linked maps that players can progress through after completing a quest with Zana, Master Cartographer.
In addition, the Atlas of Worlds also has specific "thematic" zones which enable specific base item type drops.
In the centre of the Atlas, there are 4 Tier 16 maps with special bosses which grant a single attempt at defeating the shaper after clearing the maps.
All maps, both base maps and unique maps are now located on the Atlas of Worlds. Map drops are no longer completely random like before; instead a specific tier is chosen first and the map type is chosen from pool of maps completed for that tier or connected to the map the player is currently playing. 
Each completed map base type also gives a 1% chance to upgrade the tier of a map, with values over 100% giving a chance to increase the tier a second time. The maximum map tier however can not bypass drop restrictions, even if it would have been upgraded.
For example, a rare monster in a tier 6 map with 125% completion bonus:
- a rare monster can drop +1 maps, as such it can drop tier 1 to 7 maps
- it will only drop maps that are adjacent or already unlocked on the atlas
- a tier 5 drop would be upgraded to tier 6, with a 25% chance to be upgraded to tier 7
- a tier 6 drop would be upgraded to tier 7, but can't be upgraded any further
- a tier 7 is already the highest possible drop, and can't be upgraded any further
Non-unique pre-Atlas maps from prior to Version 2.5.0 do not count towards Atlas completion, even for maps where the map type and tier are identical to the current version. Older versions of unique maps will count towards Atlas completion, however.
- Shaper's Orbs are sometimes awarded for completing a map; upgrades a map which allows "Shaped" maps to drop which are 5 tiers higher than their regular counterpart
- Cartographer's Sextants allow applying a special modifier to map, which applies its stats in a radius to other nearby maps. Those stats can be stacked, but a mod is used up after 5 uses 
- Unshaping Orbs can be used to unshape a map.
- Cartographer's Seals "uncomplete" a map.
- Masterseek (August 13, 2016). "Path of Exile: Atlas of Worlds Interview. A Map of Condensed Hype.". 2p.com. Retrieved August 13, 2016.
- Chris (August 29, 2016). "Forum - Development Manifesto - Cumulative Atlas Completion Bonus - Path of Exile". Grinding Gear Games. Retrieved August 29, 2016.