What is it?
Normally when you base you need to leave lanes in order to re-wall. If the titan has vision of the base (floater, pearl, etc.) they will most likely try to stop you, as you can be seen walking all the way up the lanes and back every time you need to place a wall, leaving you vulnerable to nukes / ward blocks. Jump basing removes these lanes, teleporting you from the safety of your base to the walls and back instantaneously.
Base:
Jump Base:
But Non, how is this possible?
There are two principles at play here,
- First is the positioning of a builder after he completes a structure; a wall walker will always exit the bottom left corner of a structure, regardless of the side entered.
- Second, WC3 pathing works on basic rules, when the square you occupy is taken up the engine assigns you to a new square automatically, the interesting part comes with how this square is decided upon. The unit defaults (or jumps) to the closest possible square of equal elevation.
Combining these two principles allows us to jump by positioning our final location (post construction) on a different elevation than our initial elevation, thus forcing the engine to physically jump the character a distance to the closest area of matching elevation. 
But Non, where can I jump base? Aren't there like 2 bases that it works with?
No, any base that is elevated can be jumped, some are just a little more difficult or more practical than others.
These are the bases that are known to be able to be jumped (in any semi-decent way):
Although I split the bases up into three categories, jump bases are subdivided into two main categories those being the leftward/downward opening bases and the rightward/upward opening bases.
Leftward/ Downward opening bases do not require offset walling, while Rightward/upward opening bases do. Each base has a Jump Line, or the line at which a wall on the right side of the line will no longer place you on the bottom left corner after cancellation or completion. While this makes sense for the leftward/downward, the rightward upward may be a little confusing. The general idea here is to find the line in which two planes of elevation meet. You can think of elevation in warcraft as a set of stairs rather than a sloping hill, with our goal being to find the drop off point from one stair to the next.
From here just fill up the base as it logically would; L/D are usually pretty cooperative, but the offset walling of R/U can leave a gap, the easiest way to close this gap is with fruits.
Some bases do not fill properly, requiring workers to fill the gaps that remain. - 4 workers = 1 shelter, or 1 worker= 1 builder - While workers do take up space they are not always reliable, especially when lumbering/moving. For the same reason that workerstacking is possible, it is possible to jump your builder on top of workers, stacking yourself inside them and putting you somewhere in the base that you do not want to be. More workers within range = higher probability of jumping to them. This also applies to using workers to lumber within the base. For this reason some jump bases must be seeded to work smoothly.
Wait non, so if I jump base I have to seed? But seed = feed
Some jump bases do have places that you can lumber at, this brings us to the second subdivision of all jump bases. While some jump bases are level and maintain a constant elevation across the entire area, others have multiple levels of elevation within the base. These Multi-elevation bases (ME) are much better than the single elevation bases because they allow room for workers, and guests.
TWERK IN PROGRESS
