If there's one instrument that became embedded in the popular consciousness of the last fify years, it's the guitar.
The guitar has of course been around for much longer than that, albeit in unamplified form. It has had serious "classical" work written for it in previous centuries as well as being an instrument of folk music, and possibly in those days exponents of either genre would have respected those of the other. In the twentieth century the guitar was taken up into jazz as part of the rhythm section, but its impact was limited in the early days by the difficulty of making itself heard above the rest of the band. In fact it seems that for most of the critical years in jazz, the hep cats were the horn players or the pianists, with the guitarist occupying a fairly low position on the ladder of hipness.
What changed all that was the discovery of amplification for the electric guitar. Pioneers like Charlie Christian and Wes Montgomery used this to promote the guitar as a solo instrument in its own right in jazz. It was not long from then until Leo Fender and Les Paul began building solid-body electric guitars, guitars that were not only meant to be amplified but which without amplification sounded almost inaudible. Actually semi-acoustic or "hollow-body" guitars remained in favour for some time and are still widely played today, but they were edged out somewhat by the solid-body Fenders and Gibsons as time progressed, not least because the solid-bodies offered the chance to rip off some shrill notes while being less prone to uncontrollable feedback.
As well as being used in jazz, including as solo instruments, guitars were prominent in white country and black blues music. The crossover from these latter genres led to them being enthusiastically embraced by the next generation of young musicians in the fifties when rock 'n' roll (arguably a synthesis of the two) arrived on the scene. Some may think that the guitar was adopted as an "easy" instrument, but that is not strictly true (see below). It does however have the advantage of being an instrument with which it is easy to project one's personality, as Elvis Presley proved. Elvis himself played a fairly basic rhythm guitar method, with his solos being played by the virtuoso Scotty Burton, which leads also to the observation that sometimes it can be something of an auxiliary instrument for a singer to play occasionally (witness, if I am not being unfair, Bono of U2). In any case early rock'n' roll and shortly after Merseybeat did not, by and large, require musical virtuosity of the sort sought in jazz: most of the songs were simple (often the three basic major chords) and often depended more upon the singer or even just having fun. Folk too, although a more serious genre (at least in the eyes of its adherents), used mainly basic chords, the intricacies being reserved for fingerpicking.
The British blues boom boosted guitar playing several notches by rediscovering the American bluesmen such as Muddy Waters and Howling Wolf and bringing them to the attention of a wider audience. Guitarists such as Clapton, Beck and Page openly acknowledged the influence of the blues, but while Clapton remained something of a purist, Beck and Page were interested in experimentation, Beck in particular mixing other scales with the blues to give an interesting sound. This was even more the case with the American Jimi Hendrix, who encompassed both the blues format and the wildest and most experimental playing in his short life. By the seventies, the guitar had become the dominant instrument in rock, perhaps overly so, although talented musicians had also pushed the level of playing up on other instruments such as bass, drums and keyboards. Apart from a spurt of interest in highly technical and neo-classical playing in the late eighties and early nineties, since then virtuosity on the guitar has not been seen as quite so important for players. On the other hand, predictions that the synthesiser would lead to the demise of the guitar in the eighties turned out to be unfounded - after the initial euphoria of MIDI and the true polyphonic synths, it was realised that electronic keyboards just could not do some things that guitars could, even with technical wizardry. Furthermore guitar-based bands came back with a vengeance with first thrash and then grunge, followed by Britpop.
Outside of rock and pop music, the guitar continues to enjoy favour in jazz as far as I am aware and on a more workaday level is used by primary school teachers and church musicians fairly regularly. It has the advantage over the piano of being portable and is quicker to learn at a basic level.
If you want to make music, learning to play the guitar has several advantages:
Before you even think about shelling out money for a guitar, you need to decide on your aims and what sort of music you want to play.
If you just want to play a few basic chords to a few simple songs, a steel-strung acoustic guitar is probably ideal for you. Some come nowadays with a socket and/or pickup for amplified playing, but if you don't intend to play outside your own home, you probably do not need this added expense.
For classical guitar playing, which is a whole discipline in itself and which will require you to learn to read guitar music, a nylon-string acoustic is usually the best instrument.
For folk or church-style chorus playing, an acoustic, amplified or not, is a good way to go, although an electric guitar may be equally useful.
For jazz, rock, pop, or any other amplified idiom, an electric guitar is usually the instrument of choice. This almost invariably requires an amplifier, although some of the semi-acoustic or hollow-bodied guitars can be played without one. Electric guitars sold these days are usually of the solid-bodied variety. Expect to pay a couple of hundred pounds when you start out for a beginner's guitar and low-wattage amp. As with most things, you can upgrade as and when you progress with your playing.
Overall, guitars, like all instruments, vary in price according to the manufacturer, the year of manufacture and the overall condition of the instrument. A low-budget foreign brand may cost between £100-£200, whereas a second-hand "name" guitar such as a Fender or Gibson with a fairly long history (ie, manufactured some time ago) may cost hundreds if not a few thousand. However, it should be noted that guitars can be bought at a beginner's level relatively cheaply and do not push the envelope of cost up to the levels of some orchestral instruments, some of which can run into hundreds of thousands.
You can ignore this section if you don't need an amp, ie you have an acoustic.
An amplifier is as much a part of the sound of an electric guitar player as the guitar itself. Everyone has their own preferences, but there are some basic guidelines:
For purely leisure play, ie on your own playing just for pleasure, 10-15 watts is probably quite sufficient
For playing in a group which has drums, 35-50 watts is really the minimum you need to make yourself heard (depending obviously to a degree on the drummer and the style of music)
Valve amplifiers are usually preferred for their sound and power to transistor amplifiers, but are usually a fair bit more expensive. A few decades ago they also had a reputation, at least in my circle, for being less reliable due to the valves going, although I do not think that this is the case nowadays.
Smaller amps tend to be "combos", ie a single unit with the head and the speaker combined. Larger units may have a separate head and cabinet with the speakers. This latter arrangement makes for flexibility (you might want to put the head with a different cabinet, for example) but does also make for extra size and weight.
It may sound obvious, but power is normally related proportionately to weight and size. You may want a big amp, but think honestly about how you will carry it, let alone transport it. TIP: if you have anything of 50 watts or over, it is often a good idea to see if you can get a model with castor wheels on the bottom. SECOND TIP: large amps mean that a Mini probably isn't your best choice of car. Think about the logistics involved, as well as where you are going to keep the amp when you are at home. In particular your parents may not want the living room dominated by an ugly great cabinet with scuffed sides that bashes the paintwork each time you stagger out to the car with it.
Many guitarists of whatever persuasion like to have a strap so that they can stand and play. Classical guitarists often have a sort of footstool instead. Electric players will need at least one jack cable to plug the guitar into the amplifier. Those guitars with jack socket inputs, whether electric or acoustic, can also benefit from electronic guitar tuners, which have fallen tremendously in price over the last decade or so and which really are worth the money both at home (if you don't have a piano to tune to or simply haven't got the ear for it yet) and in a group situation (where manic fellow musicians bashing and hammering away can make it virtually impossible to hear yourself tuning via the old-fashioned method). If you don't have a socket on your guitar, you can buy pitch-pipes which you blow to give you an idea of the note to tune to.
A case may or may not be included with the price of your guitar, but is really essential if you want to take your instrument out. Hard cases offer much better protection but are more expensive and heavier, with flight cases being the ultimate in weight and strength. Soft cases are often preferred for the lighter classical guitars since these are unlikely to have tons of other equipment plonked on top of them. "Gig bags", a sort of heavy-duty quilted case, offer reasonable protection as long as you don't place anything heavy on top of one with the guitar inside it. Even electric guitars, which are fairly resilient creatures, can be damaged by thoughtless or careless handling.
Moving up the budgetary scale, there are also guitar effects. These are electronic units that can modify the sound put out by a guitar (electric or acoustic, as long as there's a pickup involved somewhere). Much music nowadays uses effects, from a light amount of reverb to the sort of distortion and other sounds so beloved of heavy rock and related genres. The market is vast and there is no room here to discuss the different types, but modern players have had the benefit of the consumer electronic boom which has meant that in real terms the price of units has fallen over the past 20-30 years. Also, many effects units can be purchased nowadays which offer you several effects in one box, as well as sometimes throwing in a built-in drum machine for good measure. Prices vary from entry level (about £50-£100) to professional (several thousand). How essential an effects unit is to you will probably be dictated by the sort of music you want to play and whether you are in a group or not.
Lastly, unless you are a child genius on the level of the young Mozart or have played so many other instruments before that you can work the whole thing out yourself, you will probably need to find a way of actually learning. To this end you will need to purchase a guitar tutor book and possibly to consider signing up for lessons with a guitar teacher. For the former, there are quite a few manuals available on the market. For a guitar teacher you may want to ask your local music shop or check out the ads in your local paper.
Okay, let's assume that you've bought your guitar and whatever extra gear you want or need. What now? For the purposes of this discussion I am going to leave out classical playing, since I am not experienced in this area and it is a different discipline in many ways. There are many good guides if you want to get into classical.
Everyone has to learn the basics, and for most guitarists that will mean learning the basic open chords. Some people never progress beyond this level, but as they are playing mainly simple music this is rarely a problem for them. At this point virtually everyone discovers the importance of keeping their nails cut short. For most people the chords of G, A, D and E are rarely a problem, but C tends to be quite hard for a few weeks. In fact your first few weeks of playing will be as much an exercise in toughening up your fingers and fingertips as they get used to pressing against guitar strings. Don't be put off by the discomfort: this is not only natural but healthy, just as working out in the gym initially causes the body a certain amount of discomfort for it to reap the benefits later. Think of it as giving your fingers a workout.
The next hurdle for guitarists, especially electric guitarists, is the learning of bar (or barre) chords. All the initial bar chords that you learn usually involve clamping your first finger across the neck of the guitar so that it holds all the strings down firmly. This may seem impossible when you first attempt it, but with practise it becomes second nature. It may take a few months to get to this stage, however. Bar chords are used less on acoustics as a rule than on electrics: the narrower neck of the electric makes the stretching easier, but on the other hand the steel strings used on electrics can feel more painful when you start off. Don't let it put you off.
During these opening phases you will probably be learning to play chord exercises. The playing of chords on guitar in a rhythmic pattern is generally just known as "rhythm guitar". While it may seem less glamorous than whipping off a guitar solo, rhythm guitar is actually the bedrock of guitar playing and too often is neglected. I personally have had very little time for flashy players who couldn't play rhythm guitar properly, and good rhythm playing is more likely to get you into a group than knowing half a dozen strange but interesting guitar scales. Playing with a drum machine can really sharpen your abilities in this area.
After you've got the basics down, you will need to learn arpeggiated playing (playing chords one string at a time rather than all at once) and then bass runs (playing notes on the bass strings in between chords). If you want to play jazz you will also learn about those strange terms such as "flattened ninth" or "eleventh".
Once you enter the area of playing lead, things get a bit more complicated as there is more understanding of music theory required. As playing lead is largely a matter of knowing which notes and scales sound good with other notes, chords or scales, you can possibly save yourself a lot of trouble by learning basic music theory anyway. Having said that, blues scales (which often derive their sound from the harmonic or dissonant clash they make with conventional chords) are not normally covered by music theory, so you may have to experiment a bit. This is where playing along with music tracks and/or other musicians can help you enormously. Also, don't make the mistake of thinking that because you're playing lead, rhythm doesn't matter! The rhythm of a solo is as important as what notes you are putting into it. Lead guitar players that are out of time or obviously against the rhythm of the rest of the group sound, frankly, amateurish.
Finally, you need to be thinking about what you want to play in terms of material and style, while remaining open to other influences. To reiterate, when starting out you can get a lot out of playing with other musicians, even in an informal setting. Even if you play a couple of songs that you wouldn't normally have chosen yourself, it may be good practise.