There are over 60 bus lines that cover each corner of Paris. Most of the lines operate from about 7am to 8:30pm. On some lines, an evening service operates from about 8:30pm to 12:30am. Service on Sundays and holidays for many of the lines is reduced or not available.
At bus shelters or smaller stops (simple poles with bus numbers), there are maps displaying the bus route and times. Some of these have a digital board which displays the arrival times of the next two buses. Most buses must be flagged down, especially if the stop is served by multiple bus lines. The bus number and final stop are displayed above the front windshield with the number in a colored square. The buses are also color-coded, which makes it easier to follow the line on the crowded bus maps. Each bus has its color displayed on the bus stop and on the destination panels on the sides of the buses.
On the regular buses, you enter at the front and exit at the back. On the longer, accordion-style buses, you may enter at the middle or end of the bus by pressing the green Ouvrir Porte button. If you have an individual ticket, you must validate it by sliding it into the validating machine. The ticket will be returned to you and you must keep it until you exit the bus. If you have a Navigo pass, scan it over the purple target sensor. On most buses, a recorded voice and/or an electronic sign announce the name of each stop. There are also maps displayed which help you know when your stop is near. To get off a bus, press one of the red buttons that are located throughout the bus to alert the driver that you wish to get off at the next stop. Some bus doors open automatically, but others require that you press the Pour Ouvrir Appuyez button on the pole in front of the door. Buses do not make every stop on the line, only if a stop is requested on the bus or if a there is a waiting passenger at the bus stop.
You can ride any bus inside Paris for as far as you want, as well as transfer between buses and trams, with just one ticket.
As with the metro and trams, bus etiquette provides that you allow seniors, disabled, pregnant women and women with small children to sit in the front seats. There are designated areas for strollers, usually towards the back of the bus. Most bus drivers will allow those with strollers to board through the middle doors where the stroller area is. You must first request permission (sometimes this is just making eye contact with the driver as the bus approaches and nodding towards the back of the bus) and be sure to validate your ticket once you have secured the stroller and can make it safely to the front.
When you see an owl with a yellow moon at a bus shelter, know that it is one of the 42 night buses that operate in Paris and the surrounding suburbs from about 12:30am to 5:30am. Timetables vary from line to line, but they run basically every hour Sunday through Thursday and every half-hour Friday and Saturday. Normal RATP tickets are used.
Buses to the suburbs (banlieues) leave Paris from the ports on the city periphery closest to the suburb. There is a special “Autobus Banlieue” folder, available at metro information stands that gives detailed information on routes and timetables. You can also go to http://www.ratp.fr under the Plans section.