I was introduced to growing tomatoes by the ring culture method in my second year in horticulture back in 1969.
Very briefly, plants are placed in whale-hide pots (bottomless pots) and stood on a bed of gravel whereby you administer plant food via the pot but main watering is administered via the gravel [Back then the material for the gravel bed was washed, riddled ashes from the boiler house].
This method was far better than just growing straight into the greenhouse border as it eliminated soil diseases from growing tomatoes. The fibrous roots were retained within the pot and the water borne roots penetrated the gravel for water moisture.
The older method of growing straight into the greenhouse border meant that every year we would have to dig out the soil borders and sterilise it.
That’s a very brief description but it’s a little more technical than I have just described.