What is;
An arrangement
Music and songs are not set in concrete and people are not robots.
A song can be taken and working with the song structure, an alternative arrangement can be produced for a variety of reasons.
Examples;
Arrangement to; Simplify the original
Reformat to enable beginners to play
Give a diffent music style
example; A reggae beat
In short an arrangement of a song is to take the original song and make a different arrangement for a specific purpose.
An interpretation
Similar to the explanation of an arrangement. A song or musical piece can, working within the structure of the piece be interpreted in different ways. For example there are many different interpretations of well known songs. Think of original songs which have been covered and re-released by other bands or artists.
Improvising
Again working within the theme of arrangements and interpretations, improvising is placing an individual feel to a song, working within the song structure. Example; If you listen to a track on a CD, then go to watch the band in a live gig. It is very unusual for the song to be played in exactly the same way. The band and particularly the lead guitarist will improvise to enhance and give a more free feeling to the song.
Open chord
Open chords are chords where a barre is not used ie; all fingers used in playing the chord are placed only on one string each ie;
A E D C G Am Em etc
Barre or Bar chord
Chords where a finger is used to "bar" across 2 or more strings. These are difficult for beginners as they require practice to make the finger positions, also the "bar" required strength in the bar finger. In most cases the index finger is used to "bar" and other fingers are used on individual strings. ie; F Bm
Strum
To play a partial or complete chord in a single movement by either strumming up or down.
Arpeggio
An arpeggio arrangement plays strings (notes) individually rather than in a strum. As an example go to Just messin around page and select House of the rising sun which is played in an arpeggio arrangement rather than the original strumming arrangement.
Some songs contain sections in both strum and arpeggio style.
Finger picking
To play individual strings with individual fingers.
A standard format of finger picking is to use;
Finger To play
Thumb to play 6th, 5th, 4th strings
Index finger 3rd string
Middle finger 2nd string
Ring finger 1st string
Finger picking is used in playing arpeggio arrangements.