Significance of the OPEN price of the day

An open question to whoever might help

I am particularly interested in understanding the significance of the OPENING price of the day.

I would like understand its significance by observing where the open price is positioned in respect to the previous day bar or candle and ,even better, referred to a larger context; for instance its relation to the price movement over the previous 5/6 day period and resistance or support.

Am I correct in assuming that this price is largely determined by the market makers ?

And if it is so can we guess their intentions?

I would be grateful for opinions and enlightment or indications on where to find books/material covering the subject

All depends on the market in question.

The open in the index futures market is the first trade, there are no market makers in the electronic futures markets.