Swimming features four different strokes, freestyle, backstroke, backstroke and butterfly, athletes can also race the individual medley events where they use all four. Besides the individual races, relay events are also part of the programme – here, besides the traditional events, the mixed relays made their debuts in 2016 and as a novelty (and so far only featured at the Europeans) the 4x200m free relay offers one more gold for the participants.
Pool events are held over distances ranging from 50 metres to 1,500 metres. In the morning session the heats are swum while the evening features the semi-finals and finals. Based on the results of preliminaries, athletes with the best times advance to the next stage.
In the longer distances (400m and beyond) and the relays, the top eight ranked athletes directly qualify to the final, which – with the exception of the 800m and 1,500m free – is held on the same day in the evening. In the 50m, 100m and 200m events the 16 fastest swimmers from the preliminaries qualify to the semi-finals, then the top two swimmers of both semis plus the four fastest proceed to the final, staged on the following day.
At the Europeans nations can enter up to four swimmers per event but only the top two may advance from the prelims, the others shall not go through even if they also finish in qualifying positions.