Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 200

You may notice it is common practice to name a for loop variable i. Long before Java existed, programmers started using i as short for increment variable, and the practice exists today, even though many of those programming languages no longer do! For double or triple loops, where i is already used, the next letters in the alphabet, j and k, are often used.