When an individual is born, the universe is lined up in its position to the location and time of that birth. This is the natal chart or rasi chart in indian astrology. The planets are in the placement in each sign as they are in reality out there or up there. There are only 9 planets (navagraha, Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, including Rahu/Ketu as well which are the shadow planets or points of eclipse of the Sun and Moon) used due to the light from these planets are seen by the naked eye from earth up to Saturn. Planets further distanced are not visible. Indian astrology is based in the sidereal zodiac but also uses tropical zodiac in situations that apply to the karma of the planet like predicting weather and earthquakes ect but not seeing a human birth. Tropical is based in the seasons which only really further makes logical sense to the previous statement.
The placement of the planets are individual to that birth and there are further smaller amounts of time that are unfolded into charts mathematically to show further details into different areas of that individuals life. Kinda of a smaller more focused sight into the details of that larger natal chart. These charts are smaller amounts of time which change more rapidly, especially when we get into higher levels of the beings birth. In the natal chart the ascendant is the focus of the chart. The ascendent changes every two hours basically. The ascendant is the sign that is rising on the eastern horizon at the time of the birth. A person will be born into a certain degree of that sign that has risen already on that horizon. You can see how this then is just a map of what is said to be the heavens at the time of the birth. When two people are born, the higher charts (the lesser amounts of time) show the difference between these individuals as well as there are many other details in the natal chart that change besides the planets and signs which also give the individual-ness of one persons karma although the main natal charts might look the same.
There are then what are called dashas, which are time cycles, that show the impending karma that the person is experiencing during their life. The main dasha that is used is based on the moon. The moon is manas or as we translate to english, the mind, and it shows the perception of what the person is experiencing during these cycles. This is all the impending karma as said above.
There is then the transiting planets as to what is the heavens alignment at whatever time is seen, like for example what is the transits of the planets at this very moment. This transit with each planet is overlaid on the persons natal chart and is the activation of the karmas that are seen based in then the dasha that is happening in that persons life.
Just for clarity’s sake, this brings into view what is done in the general masses as horoscopes, what is said about mercury retrograde for example. When the people out there (like people making astrological forecast videos on Youtube) creating the monthly horoscopes on the net for the entertainment of individuals, when they make there statements like your forecast for the month of ________, it is based solely on a blank chart with no identification as to your own individual chart. If we all did not have any planets or any chart of our own, these ‘readings’ would be true but the simple fact is that you have your own chart and the planets in your chart are interactive with the transits. Infact, what is in your chart can completely counteract and even be completely opposite to what is said in those readings. What is even more to this is that when reading the transits they are read from a persons moon and then secondarily taken from their ascendant to see confluence in events happening. This further invalidates what is made to be a ‘reading’ of these transits in a general way and alone.
Everyone is looking out of their face thru their own lens, their own filter of everything that is mentioned above and actually much much more that I am not getting into in this superficial explanation. This is what causes the individual being. Simply put into a perspective, if there were only 12 signs and your taking everyone and putting them into these 12 signs, everything would be only in twelve possibility of ways and this is hardly individual or truth.
It all is even more complicated and vast than what I have mentioned. What bring the beauty of life is the individual-ness. Nature is diversity, obviously. We make statements about how no two snowflakes are the same. It is the same in human beings. We may all be generally made up of the same substances and the general make up of what is a human being vs the many yoni that are possible but we are at the very same time completely different in so many many many ways. The knowledge of this diversity allows one to see the play and liberation from many of its pitfalls while the simplification of it brings bondage and affliction.
Just an example of the above, when a Youtube astrologer talks about the mercury retrograde happening (or anything actually), this actually has very little to do with you individually. That transiting mercury in retrogression is going to be happening in some sign, say it is cancer as it just was, and this transit of mercury is based from your moon and then your ascendant as well. Your moon can be in 12 different signs as well as your ascendant can be one of those 12 signs. You can get the variations of this. It also has many other factors such as if your natal mercury is retrograde, the effect is greater or what the dasha is that your are in as the transit is also going to be looked at from that dasha lording planet.
When reading charts, one will also read the chart from the sun being the lagna or first house in the chart (solar chart), as well as the moon (lunar chart) is also read.
You can easily see some of the depth of Indian astrology from this and some of the details that make you and individual as well as how what is out there in the masses is purely mind fodder.