The Semitic Pê (mouth), as well as the Greek Π or π (Pi), and the Etruscan and Latin letters that developed from the former alphabet all symbolized /p/, a voiceless bilabial plosive.

Egyptian	Proto-Sinaitic	Proto-Canaanite pʿit	Phoenician Pe	Western Greek Pi	Etruscan P	Latin P

In English orthography, ⟨p⟩ represents the sound /p/.

A common digraph in English is ⟨ph⟩, which represents the sound /f/, and can be used to transliterate ⟨φ⟩ phi in loanwords from Greek. In German, the digraph ⟨pf⟩ is common, representing a labial affricate /pf/.

Most English words beginning with ⟨p⟩ are of foreign origin, primarily French, Latin and Greek; these languages preserve the Proto-Indo-European initial *p. Native English cognates of such words often start with ⟨f⟩, since English is a Germanic language and thus has undergone Grimm's law; a native English word with an initial /p/ would reflect Proto-Indo-European initial *b, which is so rare that its existence as a phoneme is disputed. However, native English words with non-initial ⟨p⟩ are quite common; such words can come from either Kluge's law or the consonant cluster /sp/ (PIE: *p has been preserved after s).

P is the eighth least frequently used letter in the English language.

In most European languages, ⟨p⟩ represents the sound /p/.

In the International Phonetic Alphabet, ⟨p⟩ is used to represent the voiceless bilabial plosive.

• A bold italic letter p is used in musical notation as a dynamic indicator for "quiet". It stands for the Italian word piano.^[2][3]

The Latin letter P represents the same sound as the Greek letter Pi, but it looks like the Greek letter Rho.

• 𐤐 : Semitic letter Pe, from which the following symbols originally derive:
  • Π π : Greek letter Pi
    • 𐌐 : Old Italic and Old Latin P, which derives from Greek Pi, and is the ancestor of modern Latin P. The Roman P had this form (𐌐) on coins and inscriptions until the reign of Claudius, c. 50 AD.
    • 𐍀 : Gothic letter pertra/pairþa, which derives from Greek Pi
    • П п : Cyrillic letter Pe, which derives from Greek Pi
  • Ⲡ ⲡ : Coptic letter Pi
  • Պ պ: Armenian letter Pe
• P with diacritics: Ṕ ṕ Ṗ ṗ Ᵽ ᵽ Ƥ ƥ ᵱ^[4] ᶈ^[5]
• Turned P
• Uralic Phonetic Alphabet-specific symbols related to P:^[6]
  • U+1D18 ᴘ LATIN LETTER SMALL CAPITAL P
  • U+1D3E ᴾ MODIFIER LETTER CAPITAL P
  • U+1D56 ᵖ MODIFIER LETTER SMALL P
• _p : Subscript small p was used in the Uralic Phonetic Alphabet prior to its formal standardization in 1902^[7]

• ₱ : Philippine peso sign
• 𝒫, 𝓅 : script letter P (uppercase and lowercase, respectively), used in mathematics. (In other contexts, a script typeface (or computer font) should be used.)
• ℘ Weierstrass p
• ℗ : sound recording copyright symbol
• ♇ : Pluto symbol
• ꟼ : Reversed P was used in ancient Roman texts to stand for puella (girl)^[8]
• Ꝑ ꝑ, Ꝓ ꝓ, Ꝕ, ꝕ : Various forms of P were used for medieval scribal abbreviations^[9]

• Mind your Ps and Qs
• Pence or "penny", the English slang for which is p (e.g. "20p" = 20 pence)

•   Media related to P at Wikimedia Commons
•   The dictionary definition of P at Wiktionary
•   The dictionary definition of p at Wiktionary