Grid slots replace reels with a larger field of symbols, often seven by seven or larger, and pay for clusters of matching symbols that touch horizontally or vertically. Winning clusters usually disappear and new symbols fall in, so a single spin can run for several steps. The minimum cluster size and the prize for each size are listed in the paytable, which on a grid game reads as a list of cluster sizes.
Casino lobbies can usually be filtered by format, feature and theme, which narrows hundreds of titles to a handful worth a look. Most games also offer a demo mode, and a few minutes of free play show the format, the pace and the features far better than a description. A game's information page names its layout and its main feature, which is enough to tell a classic from a grid game before opening it.
Classic slots copy the old mechanical machines, with three reels, a single payline or a few, and symbols such as fruit, bars, bells and sevens. They have few features or none, so almost everything depends on the base game. Their simplicity makes the rules quick to learn, and the paytable fits on one screen. Players who want plain spins without a bonus round in the background often start here, and modern versions sometimes add a single feature.