CSS layout has evolved significantly with the introduction of Flexbox and Grid, two powerful systems that have replaced older techniques like floats and clearfixes. Flexbox, introduced in 2009, is designed for one-dimensional layouts, making it ideal for aligning and spacing items in a row or column, particularly in UI components and small-scale layouts. In contrast, CSS Grid, a two-dimensional layout system, excels in handling complex designs by allowing simultaneous control over rows and columns, making it perfect for full-page structures. Both systems share alignment properties such as justify-content and align-items, offering consistency in layout design. While Flexbox is suited for simpler, linear layouts and alignment tasks, CSS Grid is better for creating intricate, structured layouts. The article underlines the importance of understanding when to use each system, suggesting that combining them can lead to cleaner, more scalable web designs. The guidance in the article has been updated as of June 2025 to reflect best practices and advancements in web layout techniques, emphasizing their distinct purposes and encouraging developers to master both for optimal design flexibility.