Tiles are almost always installed with spaces between them. This is necessary because the individual tiles are never perfectly identical. The space accommodates the slight size and shape difference between tiles. The exception to this is rectified tiles.
Standard tiles are laid with 2-3 mm of grout between them. This compensates for the slight tile irregularity. In isolation the irregularity is impermeable. But the cumulative effect over an entire floor or wall looks very uneven.
Rectified tiles have their edges very tightly trimmed, greatly reducing their imperfections. A batch of rectified tiles will be very close to uniform. This allows them to fit together almost perfectly.
Rectified tiles are used for walls or occasionally floors designed to have an almost solid look, like marble slabs on old classic architecture. In practice there are still grout lines, but these are very much narrower than the grout of regular tiles, perhaps 1 mm. This gives an almost seamless looking surface where the grout lines are never dominant. It is similar to the way solid timber planks look on a floor.
Floor Tile Perth
Consider rectified tiles for a modern style, seamless walls of marble or stone. This is very effective for kitchens or bathrooms.