In its origin the barrel It was invented by the Celts and had the function of transporting liquids or solids. However, it was later observed that gave the wine different characteristics and aromas, in addition to improving its conservation, being ideal for its upbringing.

Some of the effects of barrel aging are:
- about the color of wine: contact with the wood increases the tone due to the reaction of the tannins in the barrel with the wine.
- about the scent: the wood provides different nuances to the wine, the most common being spices and toasted.
- about the taste: the barrel adds sweetness to the wine, as well as different aromas.
After fermentation, the wine is stored in oak barrels, where it undergoes chemical changes and its composition is altered, softening the tannins. At the same time, the contact of the wood with the wine provides new nuances and flavors. In this way, more aromas will be perceived depending on the characteristics of the barrel according to its size, its use and the time the wine spends in it.
If it is smaller, newer and the wine spends a lot of time in it, it will take on more nuances. Wood qualities such as porosity and permeability, which favor controlled oxygenation, are also important. Making the barrel To make the barrels, the pieces of oak are heated to give them the characteristic curvature. This process also interferes with the properties that the wine will inherit, so that the more toasted, the less tannins it will provide.

Thus, there are four types according to the toasting of the staves:
- Light: provides vanilla and coconut aromas.
- Medium: more spicy notes, vanilla and chocolate stand out.
- Tall: Spicy notes decrease and smoked, coffee and vanilla notes increase.
- Very high: toasty and smoky notes increase.
Although the barrels have been made of different types of wood such as cherry, chestnut or pine, the most common is oak, since due to its characteristics it is the most suitable for the maturation of the wine. However, not all types of oak are suitable for this. For this reason, the most used are French oak and American oak barrels.
In the first place, regarding the performance of the wood, it is necessary to mention that the French oak needs the cut of the wood to be in the direction of the grain so that the barrels can be totally waterproof. This characteristic causes a considerable amount of wood to be wasted, being the performance of a 20-25%.
On the other hand, American oak does not have this drawback, so the cut of the direction of the grain is indifferent, with yield around 50%. On the other hand, American oak has an open pore, which allows more oxygen to the wine in less time. The same affects the nuances that the wine inherits, being a fast process, which makes it perfect for short-aged wines. However, French oak has a dense wood with a very closed pore, so the wine matures slowly.

The tannic and aromatic contribution is much greater, but also slower, being ideal for long-term aging. Lastly, we can differentiate between different types of wine according to the time it spends in the barrel:
- aging wines: They remain for a minimum of 24 months at rest in the cellar, of which 6 must be in the barrel.
- reserve wines: they must remain a minimum of 36 months at rest in the cellar, minimum 12 in barrel.
- Grand Reserve winesAge: minimum of 60 months at rest in the cellar and at least 18 months in barrel. Needless to say, this classification is in general terms, since each Regulatory Council dictates its rules and also depends on the type of wine; red, rosé or white.