Perfect pitch is one of the most enviable talents a musician can possess. It is the ability to identify and recreate a note, though it comes in two forms.
The first is absolute pitch, the ability to recreate notes without using a reference point. Someone with absolute pitch would be able to identify the note produced by everyday sounds such as a car alarm or could recreate a piece of music perfectly. It’s is believed to be a very rare occurrence with estimates suggesting that 1 in every 10,000 people possess the trait.
The second is relative pitch, which is the ability to work out the relation between two notes by using a reference note. For example, someone could play a reference note, like middle C, and then play a second sound which the listener could identify based on the reference note, i.e. “two octaves above middle C”. Unlike absolute pitch, relative pitch is a fairly common skill amongst music students, as it is the same skill we use to sing melodies by ear.
A lot of people idolise absolute pitch, not realising that they have exercised a form of perfect pitch already While absolute pitch is widely believed to be a natural skill, relative pitch is a skill almost anyone can learn. In fact, with extensive ear training it’s even possible to learn a pseudo-absolute pitch by building a relation between the name of the notes and the sounds they produce. People who have been exposed to music from an early age can develop this skill, muddying the waters about whether absolute pitch is quite as innate as some think.
In fact, a recent study on absolute 
pitch suggests that it may not even quite as absolute as it sounds. In the experiment, a student with absolute pitch was instructed to play a tune on a keyboard while the notes were secretly made flat as he played. When they notes were reset, the student believe the notes were sharp. This shows the perception of notes can be skewed.
Perhaps the bigger question is instead whether we need absolute pitch, and the answer is “probably not”. It’s certainly useful but most of us learn by ear and develop our relative pitch. In an age with pitch pipes and digital tuners, we always have easy access to reference notes to give us a proper starting point. It’s more important to worry about your familiarity with notes than someone else’s possible ability to work out notes, and to spend time practising (possibly within the context of a choir) to maintain your memory of these notes.