Certain forms of fine arts such as literature do require some knowledge to
enjoy them. However, music is one of such an exception, which can be
enjoyed even without the knowledge of it. That is why it is often said that
'SiSurvEtti  paSurvEtti, vEtti gAna rasaM phaNihi'(saMgeetamunu; SiSuvulu,
paSuvulu, pAmulu  kUDA AnaMdinca galavu). However, some curious or
inquisitive souls are never satisfied without knowing a few details of how
'music' was organized and 'what are the fundamentals that are forming it'.
Though it is an extremely tough task to address all of those aspects, this
is a simplified overview confining to some details about how the classical
Carnatic 'rAgAs' are formed based on 'svarAs'.

'nAdamE vEdamu, sAma vEdamE saMgeetam' is said to be the general notion for
Indian classical music. Sound is the first and major important component of
any music. If that 'sound' is organized in a rhythmic manner, it makes
music. The first ever 'sound' in Indian scriptures is said to be 'Om
kAramu'. From this, all the other sounds are generated and there are
'seven' sounds identified important for music. Today, it is very tough to
determine how and why only 'seven' sounds are recognized as the basis of
Indian music. These are called the 'sapta svarAs'. 'svaraM' is explained as
['(sva) svakeeyamugA (raM) raMjincu dhvani viSEshamu']. Indeed, many people
know 'sa', 'ri', 'ga', 'ma', 'pa', 'dha', and 'ni' as 'sapta svarAs'.
However, it should be borne in mind that these are only the 'indicating
letters' of 'svarAs' and actually 'svarAs' are 'sound based'. The following
is the list of the sounds of these 'svarAs'.
   ____________________________________________________________
       svara      resembles the sound of     indicating letter
   ____________________________________________________________
     shadjamamu           nemali                     sa

     rishabhamu           eddu                       ri

     gAndhAramu           mEka                       ga

     madhyamamu        kraunca  pakshi               ma
                      (a kind of crane)
    
     pancamamu      vasanta kAlapu kOyila            pa

     dhaivatamu          gurramu                     dha

     nishAdamu           Enugu                       ni
  ___________________________________________________________

Though Indian music is the same all over the country, the Western invasions
of North India in the past and the subsequent cross-cultural influence
(especially the Persian music), it is often believed that a different trend
of music called 'hindustani' came up in India. For the same reason, some
people believe that Carnatic music is relatively more 'virgin'.

These seven 'svarAs' (now I confine to using the 'indicating letters' and
Carnatic music only) have sub-variations in them. While 'sa' and 'pa' do
not have any variations and each remains as single, 'ma' has two whereas,
'ri', 'ga', 'dha' and 'ni' have three each and altogether there are 16
variations of 'svarAs'. However, once again based on the 'sound', there are
identified four duplicates. So, the ultimate effective number of 'svarAs'
to set 'rAgAs' is 
(16 - 4=) 12. 

If the 'svarAs' are rendered in the increasing order, sa, ri, ga, ma pa,
dha, ni; it is called 'ArOhaNa'(ascending) and in the reverse it is
'avarOhaNa' (descending). A 'rAga' may be described as ['svaramulacE 
alaMkariMpabaDi, janula cittamunu raMjiMpajEyu layAnvitamaina dhvani
viSEshamu']. The formation of 'rAgAs' is more of a mathematical exercise
with various permutations and combimations of these 'svara variations'.
Every rAga has specific order of svarAs. If there are '7 and 7 svarAs' in
both 'ArOhaNa' and 'avarOhaNa', it is called a 'saMpUrNa  or mElakarta
rAga'. In Carnatic music, there are 72 such rAgAs. These are called 'janaka
rAgAs' also. There are many derived out of them, which are called 'janya
rAgAs'(derivatives). From each of these 72 rAgAs, the other permutations
and combinations are also possible. If 'ArOhaNa' and 'avarOhaNa' follows
with the combination svarAs in, (7 and 6); (7 and 5); 
(6 and 7); (6 and 6); (6 and 5); (5 and 7); (5 and 6); (5 and 5); a total
of 484 rAgAs can be derived from each of the 72 original 'rAgAs', making a
total of 
72 x 484 = 34,848 'rAgAs'. I once again remind that these are all based on
the '12 variations of svarAs' only. This is the reason why some of the
'rAgAs' might sound similar for a common man (even for an uncommon man
also), but one may have a very subtle difference compared to the other,
which the experts only can distinguish. The only best way of identifying a
'rAga' is to know the eaxct 'svarAs', but not by the mere tune of the song.


(I guess, at this stage one might resort to the proverb 'ignorance is
bliss'. However, I can only say 'no pains; no gains'.)

In addition, there are 'vakra' rAgAs. These are the ones where, in
'ArOhaNa' and/or 'avarOhaNa', the 'svarAs' can occur in a 'zig-zag' manner
and not necessarily in the exact order they used to be. This aspect makes
it tough to render these rAgAs and also the number of 'rAgAs' possible
much, much, much more. One very famous example of 'vakra rAga' is 'Sree
rAga' (tyAgarAja kRti - endarO mahAnubhAvulu). 

Quite a number of film songs are tuned based on the classical rAgAs.
However, because of many factors, the film musicians can never incorporate
the original 'rAga' 100% in a song. Very often they tend to deviate from
the original and mix up a lot to get as much variety as possible. In a way,
it is not an exaggeration to say that 'light music' is also mostly either
'partially adulterated' or 'highly discounted' classical music only. 

The general method of tuning a song is based on one 'rAga'. However, as
certain 'rAgAs' are very apt for certain 'bhAvAs', different stanzas of
some 'keertanAs' or songs are set to difeerent 'rAgAs', which is termed as
'rAga mAlika'. One of the best examples is the usage of ten 'rAgAs' for
describing 'daSAvatArAs' of 'jayadEva AshTapadi-jaya jaga deeSa harE!' in
the film 'bhakta jayadEva'.

The other important aspect of music is 'tALa' (beat). In Carnatic music,
there are basically 7 'tALAs' and with each of them having 5 sub-types,
makes a total of (7 x 5 =) 35 varieties of 'tALAs'.

With regards, 
Prabhakar Vissavajjhala