Guitar neck

Neck of the guitar is the only concerned part as far as playability is considered. Your hand is always lying on this part of the guitar when you play. Hence your hand feels only this part of the guitar 100 percent of the time. A bad neck may make a thousand dollar guitar totally unplayable as compared to a hundred dollar guitar. So, it is very necessary for everyone to know about the neck of the guitar and its components too. Look at the neck given below.

You can't see, but the neck has some hidden elements too. Inside the neck there is a truss rod running all along it. The purpose of this truss rod is to counter balance the tension generated by the six strings of the guitar. If the neck would have been only made from wood, then after sometime it would bend like a bow with its crest away from the strings. The truss rod acts as a support against the strings’ tension. The truss rod is adjustable and you can change the tension on the truss rod anytime. But be careful, over tensioning the truss rod may bend the neck in just opposite direction. So you need a perfect balance. There are different types and gauges of strings, so whenever you change the type or gauge of string, you need to adjust your truss rod.

Whenever the guitar neck is bowing away from the strings, you need to tighten the truss rod. Because it shows that the strings have more tension and the neck is unable to bear it. So you need to add tension to the truss rod so that the neck can be relieved. If the bow is towards the strings, then loosen up the truss rod a little bit.
Over the neck is the fingerboard or the fretboard. The frets may be directly fitted on the neck or in many cases you will find that an additional bit of wood is pasted on the neck. And on that board, the frets are fitted. Most necks are made up of maple wood. Maple is hard and hence a good candidate for neck of guitar. The fingerboards are generally made from three woods. Maple and rosewood are the most common. Ebony is the third one. Maple looks yellowish while rosewood is dark brown. Ebony is darkest of all.
You can know if there is a neck bow or not. Take any one string and press it at the first fret and the 20^th fret. Ideally the string should touch each and every fret running from one to twenty. But generally a small relief is given in the neck and hence there will be a very small gap (around 0.5 mm) around the twelfth fret.If there is a large gap or all the frets are being touched by the string, then there is a bow. And an immediate treatment is required. The bow in the instrument originates because of the following reasons:1.    Changing temperature of the surrounding.
2.    Changing moisture content in the surrounding air. (especially during rainy season)
3.    Adding different string gauges to the guitar.
4.    Changing the tuning of guitar. (Like E flat, C flat etc.)
To deal with the first two conditions, you only need to keep your guitar inside a safe cover. For the last two, you need to adjust the truss rod anyhow.
Another very important factor that the players face is bow development while changing the strings. Do not take out all the strings at once. Take out one string, then replace it with a new one, then take out the next one.