Formed in Houston, Texas, USA, in 1970, ZZ Top evolved out of the city's psychedelic scene and consist of Billy Gibbons, Dusty Hill  and Frank Beard, the last two both ex- American Blues. ZZ Top's original line-up - Gibbons, Lanier Greig and Dan Mitchell- was also the final version of the Moving
Sidewalks. This initial trio completed ZZ Top's debut single, ''Salt Lick'', before Greig was fired. He was replaced by Bill Ethridge. Mitchell was then replaced by Frank Beard while Dusty Hill subsequently joined in place of  Ethridge.

    Initially ZZ Top joined a growing swell of southern boogie bands and started a constant round of  touring, building up a strong following. Their debut album, while betraying a healthy interest in blues, was firmly  within this genre, but Rio Grande Mud indicated a greater  flexibility. It included the rousing ''Francine'' which, although indebted to the Rolling Stones, gave the trio their first hit and introduced them to a much wider audience. Their third album, Tres Hombres, was a powerful,  exciting set that drew from delta music and high energy  rock. It featured the band's first national hit with 'La Grange' and was their first platinum album. The group's  natural ease was highly affecting and Gibbons' startling guitar work was rarely bettered during these times.

    In 1974, the band's first annual 'Texas-Size Rompin' Stompin' Barndance And Bar-B-Q' was held at the Memorial Stadium at the University Of Texas. 85,000 people attended: the crowds were so large that the University declined to hold any rock concerts, and it was another 20 years before they resumed. However, successive album releases failed  to attain the same high standard and ZZ Top took an extended vacation following their expansive 1976/7 tour.
After non-stop touring for a number of years the band needed a rest. Other reasons, however, were not solely artistic, as the group now wished to secure a more beneficial recording contract. They resumed their career
in 1979 with the superb Deguello, by which time both Gibbons and Hill had unknowingly both grown lengthy beards.

    Revitalized by their break, the trio offered a series of pulsating original songs on Deguello as  well as inspired recreations of Sam And Dave 's ''I Thank You'' and Elmore James' ''Dust My Broom''. The transitional  El Loco followed in 1981 and although it lacked the punch of its predecessor, preferring the surreal to the  celebratory, the set introduced the growing love of  technology that marked the group's subsequent releases.  Eliminator deservedly became ZZ Top's best-selling album (10 million copies in the USA by 1996). Fuelled by a series of memorable, tongue-in-cheek videos, it provided  several international hit singles, including the million-selling
 ''Gimme All Your Lovin''. ''Sharp Dressed Man'' and ''Legs'' were also gloriously simple yet enormously infectious songs. The group skilfully wedded computer-age technology to  their barrelhouse R&B to create a truly memorable set  that established them as one of the world's leading live
attractions. The follow-up, Afterburner, was another  strong album, although it could not match the sales of the former. It did feature some excellent individual moments  in ''Sleeping Bag'' and ''Rough Boy'', and ''Velcro Fly''.

    ZZ Top undertook another lengthy break before returning with the impressive Recycler. Other  notable appearances in 1990 included a cameo, playing  themselves, in Back To The Future 3. In 1991 a greatest hits compilation was issued and a new recording contract  was signed the following year, with BMG Records. Antenna  was the first album with the new company. Over the years one of their greatest strengths has been their consistently high standard live presentation and performance on numerous record-breaking  tours in the USA.  One of rock's maverick attractions, Gibbons, Hill and Beard have retained their eccentric, colourful image, dark glasses and Stetson hats, complete with an almost casual musical dexterity that has won over hardened cynics and carping critics. In addition to having produced a fine canon of work they will also stay in the  record books as having the longest beards in musical history.