Bus routes in the city are easy to master if you get hold of a copy of the transport map and remember that the routes are Color-coded: city center buses are red and always stop at one of three central squares (Catalunya, Universitat or Urquinaona); cross-city buses are yellow; green buses run on all the peripheral routes outside the city center; and Nightbuses are blue (and always stop near or in Plaça de Catalunya). In addition, the route is marked at each bus stop, along with a timetable - where relevant, bus routes are detailed in the text.
Most buses operate daily , roughly from 4 or 5am until 10.30pm, though some lines stop earlier and some run on until after midnight. The Nightbuses fill in the gaps on all the main routes, with services every thirty minutes from around 10pm to 4am - for these, you can buy single tickets (€1), or a nitbus targeta for €6.40 which is valid for ten rides and available on the bus itself.
Between April and November, there's also a tourist bus , the Bus Turístic (#100; daily 9am-7pm; every 20min), starting at Plaça de Catalunya and linking all the main sights and tourist destinations, including the Sagrada Família, Parc Güell and the Poble Espanyol. The buses are Color-coded according to their direction: red destination boards indicate northbound services and blue are for southbound. Tickets cost €13.30 and are valid for one day, allowing you to get on and off as you please; a two-day fare costs €16.10 and a child's ticket is €7.90. The ticket also gives discounts at various sights and on other transport systems, such as the tram to Tibidabo.
Out of Barcelona, and away from the main routes, buses will probably meet most of your transport needs and on the whole they're reliable and comfortable enough, with prices pretty standard at about €4.20 per 100km. Timetables are posted at bus stations and, usually, in local tourist offices. It's worth noting that the bus service is drastically reduced on Sundays and holidays - it's best not even to consider travelling to out-of-the-way places on these days. The (Catalan) words to look out for on timetables are diari (daily), feiners (workdays, including Sat), and diumenge or festius (Sun and holidays).