Types of infected
Infected all look different, but they move in different ways. Shamblers and crawlers are slow; runners chase you faster than you can jog.
A crawler is still dangerous while you deal with something else.
Sight and sound
Infected see quite far ahead in a wide field of view. It takes them a moment to recognise you, and they lose track of you soon after you break line of sight. Noise attracts them, even from behind.
Sprinting is louder than jogging, walking, crouching or crawling. A suppressor makes a shot quieter, not silent.
Their attacks
A neck bite hurts more than a normal blow, and a jumper’s leap hits harder still. Armour helps.
Aim for the head – headshots do far more damage. Keep an escape route and enough stamina to get away from a group.
They only reach you on their own floor and with nothing solid in between – a wall, a ceiling or a closed door stops their attacks.