Crawling typically starts between 7-10 months, but range is wide (6-12 months is normal). Many styles: traditional hands-and-knees, army crawl (belly on floor), scooting on bottom, crab crawl (backward first). Some babies skip crawling entirely and go straight to walking - this is normal! Once mobile, serious baby-proofing is essential. Baby can get into dangerous areas quickly.

Hand-eye coordination develops gradually: Batting at objects (3 months), purposeful reaching (4 months), grasping successfully (5-6 months), transferring objects between hands (6-7 months), pincer grasp (8-10 months). Early reaching is inaccurate - baby swipes at objects and misses. With practice, becomes more precise. Grasping starts as whole-hand "raking" motion, progresses to thumb-finger pincer grasp. Crucial for self-feeding, playing with toys, and later writing skills.

Object permanence is understanding that things continue to exist even when you can't see them. Develops around 4-7 months, fully established by 8-12 months. Before object permanence: Baby thinks objects cease to exist when hidden ("out of sight, out of mind"). After: Baby knows you still exist when you leave the room, will search for hidden toys. This cognitive leap explains why separation anxiety starts around 8 months - baby now knows you exist elsewhere and misses you!