This explanation taken from the Treccani encyclopaedia, I find it deficient and I would like your contribution on it:
 

"Tides are movements of the sea caused by gravitational forces. They are characterised by regular periodicity and amplitude, and for this reason they have always been a constant reference for man. It is no coincidence that in some populations the tides were called with terms that recall the passage of time. The intensity of the tides is not the same throughout the Earth and in some areas they have spectacular effects.

​

​

When the sea invades the land

Tides are a periodic and regular movement of lifting and lowering of sea water caused by gravitational forces acting in the Earth-Moon-Sun system. There is probably no better place than Mont-Saint-Michel, in the North-West of France, to experience the astonishment caused by the sea invading the territory at high tide. This picturesque medieval fortress about twice a day becomes practically an island. The sea advances dizzyingly from the low tide line, a few kilometres away from the coast, preceded by a deaf roar that makes you astonished. A thousand rivulets of sea water regain the land just before dry, in a tumult of foams which, according to the description of the writer Victor Hugo, "advances as fast as a galloping horse".

The regularity of the tides has always been a temporal reference point for the coastal populations of the past. In several Nordic languages the connection between tide and time can still be understood today: tide and time in English, getijde and tijde in Dutch, Gezeiten and Zeit in German.

​

​

Generating forces

The tides are essentially caused by the combined action of two forces: the gravitational attraction exerted by the Moon on the water mass and the centrifugal force that arises from the reciprocal movement of the Earth and the Moon in space. The Earth rotates around its own axis and, at the same time, the Earth and the Moon together make a motion of revolution around an ideal axis, which corresponds in the first approximation to the orbital motion of the Moon around the Earth. This means that in the course of a day the points on the Earth's surface are subjected to the action of a force that varies over time.

Let's consider, for example, the high tide condition that occurs in an area twice a day, exactly twice in 24 hours and 50 minutes (semi-durnal tides): when the Moon transits on the local meridian, and 12 hours and 25 minutes later when it transits on the same meridian but at the antipodes (i.e. at the diametrically opposite place on the Earth's surface). It is easy to understand why the flow of the high tide manifests itself in the first configuration: in fact in this case the Moon is closer and can exert a greater force of attraction on the water which tends to swell. Less intuitive is the second case, in which the lifting of the water is determined by the centrifugal force (the same that two people experience when holding their hands and rotating rapidly around the point of grip), which is prevalent here.

As soon as the high tide flow is completed, the sea level reflux occurs, culminating, after 6 hours and 12.5 minutes, with the low tide when the area concerned is at maximum distance from the alignment with the Moon.

Like the Moon, the Sun also produces a tidal action which is, however, less effective due to the considerable distance between the Earth and the Sun. On full Moon and new Moon days, when the Sun, Moon and Earth are astronomically aligned, the tides have maximum intensity (live tides).

​

​

Local variations

If the Earth were entirely covered by the oceans on a homogeneous seabed, the gravitational forces would produce uniform tides with the characteristics just described. On the other hand, the presence of the emerged lands and the differences between the various ocean basins mean that the tides have different delays, frequencies and intensities; they differ from zone to zone. As a consequence, there are places where the tides are a few minutes late with respect to the passage of the Moon on the local meridian and others where the delay is a few hours; places with only a daily flow and ebb (daytime tides); places where the difference in sea level between high and low tide (tidal amplitude) is considerable (for example in Fundy Bay in Nova Scotia, the amplitude is 19.6 m) and others where it is reduced. In the oceans and seas there are also some singular points (called amphidromic) that are not affected by tidal fluctuations."

 

​

As can be seen from the text, there are some questions that cannot be answered:

 

1- How does the gravitational force of the Moon act so clearly in some areas of the seas and less so in others? Take for example the Mediterranean Sea where the tides have a ridiculous intensity compared to other parts of the world.

 

2- What are the singularities, which also cover at least 20% of the seas, called "amphidronic" points? 

 

3- If the centrifugal force of the earth's rotation is part of the origin of the tides, why is there a marked concentration of the same even in parallels so far from the equator where the same force is clearly lower?