Pockets are classified in three categories.
1. Outside pockets
2. Inseam pockets
3. Welt pockets
1. Outside pocket/patch pocket.
E.g. pocket on shirts, pockets on jeans.
2. Inseam pockets.
E.g. Side pockets on trousers and skirts.
3. Welt pockets.
E.g. chest pocket on jackets and back pockets on trousers.