Lead guitar refers to a role within a popular music band, especially a rock band, that provides melody or melodic material, as opposed to the rhythm of the rhythm guitar, bass, and drums. A lead guitarist typically plays solos, riffs and fills. Solos are improvised or written passages played with the accompaniment of the rest of the band often at the song's climax. Riffs are usually song introductions and often repeat for the duration of the song. Fills occur during the pauses of the lead singer's parts between phrases or sections.
With the advent of hard rock, metal and grunge, the role of the lead guitarist became more varied and often virtuosic. Speed picking, arpeggiating and fret tapping are some of the techniques used by today's guitarists to maximize the speed of their riffs.
Lead Piece: almost any rock song has a lead piece (or break) or a section where the vocals give way to the guitar to take the main melody line of the song. Often in rock music, introductions and outros are also taken on by the lead guitarist.
Effects: almost always played through a series of modulating and distorting effects, the lead guitar styles are often characterised by the individual sound of the artist. A majority of the famous guitarists have a regular set of effects which define their sound, making it similar in some ways to the variation in individual voices.
Style: In addition to the sound of the guitarist's instrument, effects and amplification equipment, many players exhibit a style of playing which marks them out in a similar way to their tonal signature. The use of particular scales, the length of notes played and the way they are bent (a technique in which a string is pushed sideways, along the fret to increase its pitch), in addition to creating a worthwhile performance, will also allow the playing of many well-known guitarists to be identified by listeners. (Courtesy of Wikipedia)
A well-rounded guitarist should have a familiarity with both basic types of guitar playing: Rhythym and Lead. Click below for the best free Lead Guitar lessons available on the web.