Low Gallifreyan (also known as Circular Gallifreyan) is the language used in Gallifrey post-Rassilon. It's one of the the two official languages used in the High Council (the other being High Gallifreyan) and the language in which the Doctor's TARDIS displays information. The Doctor himself writes sticky notes throughout the TARDIS in this language.
The language consists of a Base Shape, either a circle or hexagon, in which different shapes are displayed, all painting a symbolic image of what is being explained. The language is deciphered, not read, and is especially useful in TARDISes for co-ordinates, scanner readings, and many others. Low Gallifreyan is a much more simplified version of High Gallifreyan (not to be confused with Old High Gallifreyan) and is commonly used in High Gallifreyan Scripture.
The Low Gallifreyan Number System is a base-7 system, consisting of seven numerical symbols, which are placed within an octagon. Being a base-7 system, it is confusing for most other races in the universe, as base-7 is not used on any other planet.
DeviantARTist DrawlingNell is going to be contributing Low Gallifreyan and High Gallifreyan scriptures to the Dictionary.
The name does not signify a lower social group or status, however the reasoning behind the name otherwise is unclear. One possibility is that it may refer to the specific regions of Gallifrey in the same way that the terms Upper and Lower in ancient Egypt referred to specific regions of Egypt (where Lower Egypt was the Nile delta land to the north and Upper Egypt was the southern portion of Egypt).