The straight answer to "roulette european rules" is found at the wheel. Roulette looks like pure chance, and it is, but the rules still decide how much any bet costs. A European wheel has one green zero, an American wheel adds a second, and French tables add rules that return half of some losing bets. Knowing which wheel is in play, what each bet pays and what the zero takes is most of what there is to know about playing roulette sensibly.
The best odds in roulette are on a single zero wheel, and better still under French rules. European roulette keeps an edge of about 2.7 percent; French tables add la partage, which gives back half the stake on even money bets whenever zero lands and so halves that edge on those bets. French layouts also take call bets placed by name, such as the neighbours bet on a number and the two either side of it on the wheel. Knowing how to play French roulette mostly means knowing those extra rules.
Roulette odds come straight from the wheel. On a European wheel there are thirty seven pockets, so the chance of landing on green is one in thirty seven, and on a double zero wheel one in thirty eight. Red and black each hold eighteen pockets, and neither color wins more often over time; a streak of one color says nothing about the next spin. The color rules are simple: zero counts as neither red nor black, so even money bets lose whenever it lands.
A European wheel has a single green zero, an American wheel adds a double zero, and French tables use the single zero with rules returning half some losing bets.
Choosing a single zero wheel, holding to a fixed budget and knowing when to stop is the only approach that works, since the edge stays constant.
Each spin charges the same share of the stake, so a live table at about forty spins an hour drains a budget far slower than a fast online game.
Neither: each colour holds eighteen pockets, streaks say nothing about the next spin, and zero counts as neither, so even money bets lose on it.