Spritz (Italian light cocktail)

For ➊
3 parts  white wine, sparkling wine like prosecco or spumante preferred, cooled
2 parts  aperitivo like Aperol (or Campari for a more bitter taste), cooled
2 parts  selzer or soda water, cooled
a slice of orange (or lemon when using a strong aperitivo)
some ice

Pour the wine and the aperitivo in a tumbler or stemmed wine glass. Add sparkling water (from a syphon if available). Add some ice and a slice of orange.
Serve with small bites of Italian snacks.
When Austria reigned the North of Italy, they developed a habit of diluting the wine with water, called 'Spritzer'. Italians rethought the formula by adding a bitter aperitivo to (sparkling) white wine, and tipping it with a splash of sparkling water, hence the Austrian name 'Spritz' or 'injection'. The typical Venetian spritz has 3 equal parts of each ingredient, other recipes tend to use 40% of wine, and 30% each of water and aperitivo. When using a sparkling wine and a low alcoholic aperitivo like Aperol, you can omit the sparkling water or limit it to a splash, 6 cl wine, 4 cl Aperol, splash of soda, the classic recipe of Aperol since 1950.
Normally, a red/orange aperitivo is used, but it can be replaced by others, like Cynar, or even the  orange-based curaçao blue (resulting in a blue cocktail).