title_body: What is the highest alcohol content achievable through brewing?
upvoted_answer: That depends on what you mean by "naturally".  There are some strains, such as the "Super High Gravity Ale Yeast" by WyLabs, which can handle up to 25%.  But there are techniques, such as freezing the beer to create a more concentrated product, which have been used to get up to 60+%.  In this case, alcohol is not added, but rather, water is removed, altering your ABV.