In the New Testament
Philip, from Bethsaida — the same town as Peter and Andrew (John 1:44) — is called directly by Jesus with the simple words "Follow me" (John 1:43), and immediately goes to find Nathanael (Bartholomew), inviting him with the now-famous line "Come and see" (John 1:45–46). John's Gospel gives Philip more individual dialogue than most of the Twelve receive: before the feeding of the five thousand, Jesus tests him by asking where they might buy enough bread for the crowd, and Philip's practical, slightly overwhelmed answer ("Two hundred denarii worth of bread would not be enough for each of them to get a little," John 6:5–7) reveals someone thinking in very human, logistical terms even in Christ's presence. Philip is also the apostle approached by a group of Greeks wanting to see Jesus near the end of his ministry (John 12:20–22), and, at the Last Supper, asks the request that prompts one of Jesus's most quoted answers: "Lord, show us the Father, and that will be enough for us," to which Jesus replies, "Anyone who has seen me has seen the Father" (John 14:8–9) — a moment of Philip voicing exactly the question any honest disciple might still want to ask.
Note: Philip the Apostle (one of the Twelve) is a distinct figure from Philip the Evangelist, one of the seven deacons chosen in Acts 6 and the man who baptizes the Ethiopian eunuch in Acts 8 — the two are easily confused, and some ancient traditions about "Philip" may conflate details from both men.
Later mission and martyrdom tradition
Tradition places Philip's later ministry chiefly in Hierapolis, in Phrygia (modern-day Turkey), where he is said to have died — accounts vary between martyrdom by crucifixion (some traditions specifically say upside down, echoing Peter, and also claimed of Andrew, suggesting these details may have cross-influenced each other in later legend) and other traditions describing death by stoning or hanging. Archaeological excavation at Hierapolis in 2011 uncovered what excavators identified as a tomb traditionally associated with Philip, lending some physical weight to the tradition of his ministry and death there, even though the precise historical details of his martyrdom remain uncertain.
Why it matters
Philip's small, human moments in John's Gospel — doing the practical math on feeding a crowd, and simply asking to see the Father plainly — make him one of the more relatable figures among the Twelve: not a dramatic convert or a headline leader, but someone who kept asking honest, slightly uncertain questions right up to the night before the crucifixion, and got a real answer each time.