客 is used in: 客人 (guest), 顾客 (customer), 客厅 (living room), 客气 (polite/courteous), 乘客 (passenger), 旅客 (traveler). A roof (宀) over each (各) - each person under your roof is a guest.
Roof radical on top - the indexing component, putting 客 in the dwelling family with 家 (home), 室 (room), 安 (peace under a roof), 守 (guard the house). The roof here shelters whoever has come to visit.
Bottom 各 gives the sound (gè → kè, mild drift) and a soft semantic touch - each individual person who arrives under the roof. Same phonetic family as 格 (pattern), 路 (road), 落 (fall) where 各 keeps a rough -è/-uò reading.
