If you plan on visiting other parts of Ireland, it can be handy to use the train. The main train station, railway station, in Dublin is the Connolly station. The station is located on the northern side of River Liffey, but the station is connected to the southern side of Dublin as well. It is normally said that Conolly station serves the east coast of Ireland and to Sligo while Heuston Station (on the southern side of River Liffey) serves the south and west of the country.
The DART (Dublin Area Rapid Transit) is part of the suburban railway network in Ireland, running mainly along the coastline of Dublin Bay on the Trans-Dublin route, from Greystones in County Wicklow, through Dublin to Howth and Malahide in County Dublin.
IF you would like to use the railway system in Ireland, visit irishrail.ie for information, schedules, prices and much more. Here you can also find promotions, discounts and other cool stuff. If you plan on visiting Belfast while in Dublin, using a train is a very good way of doing so.
If you would rather travel by bus, then you can visit Bus Eireann for more information, prices, schedules and more!