Plus code
Plus codes are a system for expresing geographical locations, intended to be used in place of street addresses when those are unavailiable or inconvenient. They encode the latitude and longitude of a rectangular area in a base-20 system using a set of 20 number and letter characters (selected to avoid ambiguities like the letter O and the number 0, and to avoid letters that may spell recognizable words in any language including those that might make middle-schoolers giggle). The size of the rectangular area depends on how many "digits" (the developers use "digit" to refer to all the encoding characters even though some are letters) the code has; a plus sign is included to mark a specified point in the code so that digits can be omitted at the end to use lesser precision, or at the beginning because when you already know what country or city a place is in you might not need the larger areas narrowing it down from the entire world (the coding scheme is such that nearby places are usually all within the same upper-level prefix of codes, so it can be omitted as country and area codes can be omitted from phone numbers within a local area).
This coding system was developed by Google engineers and implemented within Google Maps, but it is open-source and free for anybody to use.
