Most people remember from their school days that the coastal tides are humps of water, directly caused by the gravity of the Moon and the Sun. Recall those pictures of the Sun and Moon lining up, causing a heaping effect directly underneath (and opposite) them? Most popular science articles still explain it that way.
Well, it is not quite how coastal tides work. It is true that Earth's crust bulges out a bit under the direct gravity of the Sun/Moon, but the oceans 'lift' and 'drop' with the same amount as the crust, so… no coastal tides. Since coastal tides happen, where do they come from? The answer lurks in tidal currents that circulate very slowly, driven by the 'tractive components' of the Moon/Sun's tidal gravity. Combined with harmonic oscillation of water in some basins, these currents create relatively large coastal tides in many areas.
Read a NOAA article Our Restless Tides for a semi-technical discussion on tides. Visit Tidal Gravity for an engineering-like article on tidal gravity and the tides.
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