It's completely normal for babies to have cold hands and feet, even when they're warm and comfortable. This happens because babies' circulatory systems are still developing - blood goes to vital organs (brain, heart, lungs, digestive system) first, leaving less for the extremities. Babies don't regulate temperature as efficiently as adults. Their hands and feet can feel cool even when their core body temperature is perfect. This is especially common in newborns and continues through the first year as circulation matures. The best way to check if baby is the right temperature is to feel the back of their neck or chest - these should be warm (not hot or sweaty, not cold).

Colic: inconsolable crying 3+ hours per day, 3+ days per week, for 3+ weeks (Rule of 3's). Usually starts around 2 weeks, peaks at 6 weeks, resolves by 3-4 months. Typically occurs same time each day (often evening). Baby pulls legs up, clenches fists, face turns red, passes gas. Otherwise healthy and feeding well. Cause unknown - theories include immature nervous system, gas, overstimulation. NOT parent's fault.

Tantrums typically begin 12-18 months and peak around age 2-3. Early tantrums involve crying, screaming, arching back, throwing things, hitting, or going limp. Causes: frustration at limited language/abilities, tired, hungry, overstimulated, seeking independence, testing boundaries. This is NORMAL development - baby has big feelings but lacks skills to regulate them. Brain's emotional center develops before logical center.

Newborns cry 2-3 hours per day on average (some more, some less). Crying peaks around 6 weeks, then gradually decreases. Crying is baby's only way to communicate needs: hunger, tired, wet diaper, too hot/cold, overstimulated, needs comfort, gas/discomfort. The 5 S's (Dr. Karp): Swaddle, Side/stomach position (while holding), Shush, Swing, Suck. These trigger calming reflex.

Babies have immature nervous systems and can become overwhelmed by too much stimulation: noise, lights, activity, people, toys. Signs of overstimulation: arching back, turning head away, avoiding eye contact, fussiness, crying, hiccups, yawning, clenched fists, jerky movements. Newborns especially sensitive - can only handle 15-30 minutes of active play before needing break. Overstimulation often causes evening fussiness and difficulty settling for sleep.

Separation anxiety typically begins 6-8 months and peaks around 10-18 months. Baby cries when you leave the room or when held by others. This is HEALTHY development - shows secure attachment and understanding that you exist when not visible (object permanence). Symptoms: clinginess, crying when you leave, distress with strangers, waking more at night, resisting bedtime. Usually improves by age 2-3 as child gains independence and language skills.

Stranger anxiety begins around 6-12 months. Baby cries, turns away, or clings when approached by unfamiliar people (even grandparents they don't see often). This is normal cognitive development - baby can now distinguish between familiar and unfamiliar faces and prefers familiar. Peaks around 12-15 months, gradually improves as toddler becomes more independent. Not a sign of poor socialization - it's healthy development showing secure attachment to caregivers.

Teething typically starts 4-7 months (can start as early as 3 months or as late as 12 months). Symptoms: Drooling, chewing on everything, irritability, mild gum swelling, low-grade fever (<100.4°F), disrupted sleep, cheek rubbing or ear pulling. Teething does NOT cause: High fever (>100.4°F), vomiting, diarrhea, severe fussiness, rash all over body. If these occur, baby is sick (not just teething). Bottom front teeth usually come first, then top front, then sides. Process takes 2-3 years to complete all 20 baby teeth.