In the broadest sense, red wine is made by pressing red grapes to extract the juice, and then fermenting that juice to convert the sugars in the juice to alcohol.

However, there are number of choices that the winemaker can make during the process that can affect the style, structure and flavour of the wine.

• Grape selection – there are many different red grapes available for winemaking. Some red grapes (like Cabernet Sauvignon and Malbec) tend to make richer, deeper coloured reds. Others (like Pinot Noir and Sangiovese) tend to make lighter, more elegant reds. Whichever grapes are used, a good winemaker will sort the grapes before pressing to ensure only the ripest and best are used.
• Pressing – the grapes are then pressed to extract the juice. In the case of red wines, the juice will be left in contact with the grape skins for up to 30 days. The longer the juice stays on the skins, the more body, colour and tannin the wine will have. Tannin gives the wine structure or ‘grip’ – and allows it to age gracefully.
• Fermentation – in most cases yeast is added to the must (the pressed juice) to start fermentation, but sometimes natural or wild yeasts are allowed to start the process naturally. Fermentation can take place in a variety of vessels. Each will affect the final wine in a different way. Here are three common examples.

1. Temperature-controlled stainless-steel tanks – good for producing fresh, fruity reds and offer very reliable consistency.
2. Open concrete vats – these sound unromantic, but actually can produce beautifully soft textured reds.
3. Oak barrels – expensive and only used for fine reds. They allow the wine to micro-oxygenate during fermentation, resulting in beautifully smooth reds. Can impart some subtle oak flavours to the wine.

• Clearing – after fermentation, red wines are cleared. Sometimes this is done by adding egg whites or other ‘finings’ to encourage any left-over yeast to drop to the bottom of the vessel before the wine is drained off. Sometimes the wine is filtered. And occasionally the wine is left to clear naturally and ‘racked’ – a process where it is regularly drained off into new containers to allow it to clear slowly of its own accord.  
• Maturation – most wines will be matured for at least a short while to allow the flavours to integrate and tannins to soften. Some will be matured in a combination of barrel and bottle for much longer. Ageing in barrel allows micro-oxygenation – helping to speed up the maturation process – and can add notes of cedar or vanilla (depending on the source of the oak). Maturing in bottle allows the tannins to soften, and lets the wine develop secondary flavours. (Primary flavours are fruit, while secondary flavours can be earth, spice, leather, forest floor and more). 

This is a just a quick overview of how red wine is made. Different regions have their own methods – such as the appassimento technique used for Amarone. Added to the huge number of grape varieties and growing regions in existence, these techniques can produce a dizzying and delightful array of red wine styles.