Planets are four signs apart, usually in the same element (Fire, Earth, Air, or Water). The most harmonious aspect. Energy flows effortlessly between the planets. It represents natural talents and areas of life where things "click" without much work. However, because it is so easy, it can sometimes lead to passivity.
The astronomy in these guides is computed, not copied: sign boundaries, aspect angles and planetary positions are calculated on StarBind's own servers from the same JPL planetary data NASA uses, accurate to fractions of an arcsecond.