的 is the most common character in Chinese. It connects a modifier to a noun: 我的 (my), 红的 (red one), 大的 (big one), 吃的 (something to eat).
mistakes
Don't confuse 的 (de, possessive), 得 (de, after verbs for degree), and 地 (de, before verbs for manner). They sound the same but have different grammar roles.