It's the mint mark for Philadelphia, the same as on coins minted there since 1980.
When the nickel's composition was changed in late 1942 due to wartime metal shortages, the coin's mint mark was made larger and moved from the right to Monticello to above its dome to indicate the new alloy. The letter "P" was used for the first time on any US coin, along with D (Denver) and S (San Francisco).
No such coin exists. All 1942-D nickels are made out of the standard 75% copper 25% nickel. Only 1942-S and 1942-P nickels were struck out of the "war nickel" alloy of 35% silver. A 1942-D nickel is worth about 7 cents if circulated and a couple of bucks if in better shape.
Average circulated, about $22
It is an American nickel made of copper, silver and manganese during World War 2.
Just going by silver content, they're worth about $2 each.
What you actually have is a counterfeit nickel, known as a Henning nickel. This isn't a war nickel, but instead was a counterfeit nickel created in the mid-1950s, there is a thriving collectors market for them. I've attached a link with more information about the Henning nickels.
The "P" mintmark shows that the coin was produced by the US Mint at Philadelphia.
Five pennies in a nickel. (US coinage)
The large "P" above the dome means it's a "war nickel" that is struck in 35% silver. The nickel was removed for the war effort and silver was used as a replacement, this was done from 1942 - 1945. Because it has a small amount of silver the value is about $1.00. NOTE: The 1942 war nickel is the first US coin to ever use a "P" Mintmark.
It is known as a "war nickel" and actually contains no nickel! But it is 35% silver and is worth about $1.25 for the silver content.
That's a silver war nickel from WWII, which contains 35% silver. It's worth about $2.
That's a silver war nickel, containing 35% silver, and it's worth at least $2.
That is known as a "war nickel" to save nickel for the war effort, the US government replaced some of the nickel in the nickel with silver. At the time of writing the silver content in them is around $1.70. The reason for the mintmark over the Monticello was that the idea was that people would know they contained silver.
That is a "war nickel". War nickels minted between 1942-45 are identified with a large P, D, or S above the Monticello on the back. These nickels are 35% silver, and so have a definite value. The idiot who says they're worth "about 5 cents" is stupid.
Same as any nickel, the P means it was minted in Philadelphia, Pennsylvania
The P mint mark was only used on the back of nickels dated 1942 to 1945. If that's what you have it's a so-called "war nickel" made of copper, manganese, and silver as a means of conserving nickel for the war effort. They sell for about 80-90 cents in circulated condition. Nickels dated 1980 and later may have a P or D on the front, but they're only worth 5 cents.
That is what is known as a war nickel, because nickel was needed for WWII, it was needed to change the composition of the nickel to one including 35% silver, as of the time of writing, your coin is worth $1.64 in silver content alone.
The letter P in the designation of aircraft during the World War II period (e.g. P-36 Hawk) represented Pursuit.