Conjunctions, oppositions, trines, squares and sextiles are the traditional aspects and are usually considered "major". Quincunxes, sesquiquadrates, semi-squares and semi-sextiles are considered minor. Some say the sextiles and quincunxes are "intermediate" aspects, not as important as the major, but more influential than the minor ones. However, in practice, the "strength" and nature of each aspect have much more to do with the planets or points involved than the aspects themselves.
The aspects are angles that planets make to each other, but in other words they are simply divisions of the zodiac wheel: the opposition is a division by 2, the trine a division by 3, the square a division by 4 and so on. Since there are 12 signs, 4 elements (fire, earth, air, water) and 3 modalities (cardinal, fixed, mutable) and together they form the most basic framework with which we can interpret the chart, these divisions always point to predictable, repetitive themes.
Trines occur when planets/points are 4 signs away from each other, meaning they are of the same element but a different modality. They are naturally attuned and their energies flow together, combining the different modalities with ease, thus usually bringing positive results. Sextiles (which are "half-trines") occur when planets/points are 2 signs away from each other. In this case, they are in different but complementary elements (Fire-Air, Earth-Water) and, even though they go well with each other, their expression isn't as natural as with the trines and this is why they are considered weaker.
Oppositions occur when points are 6 signs away from each other and, being so different in nature (literally opposites), the signs involved are conflicting, but can be worked with since they are of complementary elements and the same modality. Squares, occurring when points are 3 signs away, can be even more tense and challenging. The points are in very distinct signs, of conflicting elements, but also in the same modality. They can be resolved with time and knowledge, but often cause many problems.
Conjunctions are regarded as most important because they unify the natures and energies of two planets in one sign, element and modality, whether or not the planets themselves are compatible. Together, they have an unimpeded channel of expression (unless adversely aspected by other planets) through the sign they're in; therefore they are often promptly apparent in one's life or way of being, for better or worse.
This was supposed to be a brief explanation, but I guess this is for everyone who wants to know more about aspects. I hope it helped somehow.
The aspects are angles that planets make to each other, but in other words they are simply divisions of the zodiac wheel: the opposition is a division by 2, the trine a division by 3, the square a division by 4 and so on. Since there are 12 signs, 4 elements (fire, earth, air, water) and 3 modalities (cardinal, fixed, mutable) and together they form the most basic framework with which we can interpret the chart, these divisions always point to predictable, repetitive themes.
Trines occur when planets/points are 4 signs away from each other, meaning they are of the same element but a different modality. They are naturally attuned and their energies flow together, combining the different modalities with ease, thus usually bringing positive results. Sextiles (which are "half-trines") occur when planets/points are 2 signs away from each other. In this case, they are in different but complementary elements (Fire-Air, Earth-Water) and, even though they go well with each other, their expression isn't as natural as with the trines and this is why they are considered weaker.
Oppositions occur when points are 6 signs away from each other and, being so different in nature (literally opposites), the signs involved are conflicting, but can be worked with since they are of complementary elements and the same modality. Squares, occurring when points are 3 signs away, can be even more tense and challenging. The points are in very distinct signs, of conflicting elements, but also in the same modality. They can be resolved with time and knowledge, but often cause many problems.
Conjunctions are regarded as most important because they unify the natures and energies of two planets in one sign, element and modality, whether or not the planets themselves are compatible. Together, they have an unimpeded channel of expression (unless adversely aspected by other planets) through the sign they're in; therefore they are often promptly apparent in one's life or way of being, for better or worse.
This was supposed to be a brief explanation, but I guess this is for everyone who wants to know more about aspects. I hope it helped somehow.
