By plane
Most major European airlines such as Lufthansa, Air Berlin, British Airways, Air France, Iberia, Alitalia, TAP Portugal, Turkish Airlines fly daily to Algiers but there are also some long-haul routes such as Beijing, New York, Montreal, Doha
From the United Kingdom flying via Barcelona or Madrid can be cheaper than flying direct.
From the United States the cheapest way to get into Algiers is via London British Airways, Paris Air France or Frankfurt Lufthansa.
The national airlines Air Algerie flies to many destinations in Europe especially France but also to some cities in Africa and the Middle East. All destinations served by Air Algerie from Algiers : Abijan, Alicante, Bamako, Barcelona, Brussels, Basel, Beijing, Beirut, Berlin, Cairo, Casablanca, Dakar, Damascus, Dubai, Frankfurt, Geneva, Istanbul, London, Madrid, Milan, Montreal, Moscow, New York JFK, Niamey, Paris, Rome, Tripoli, Tunis.
For more information about the Algiers airport check the official site Aéroport d'Alger.
By ship
The prices are usually more expensive than flying so if you can and have no car take a plane. Most connections are offered by Algerie Ferries (http://www.algerieferries.com).
From/to Spain:
Alicante to Algiers and Oran
Almeria to Gazhaouet
Barcelona to Algiers and Oran
From/to France:
Marseille to almost every Algerian harbor Annaba, Skikda, Bejaia, Jijel, Algiers, Oran
From/to Italy:
Napoli to Tunis & take a road for 1 hour
Roma Civitavecchia to Tunis & take a road for 1 hour
By train
The Algerian train company is named SNTF (http://www.sntf.dz), tickets can be bought at the Train stations, unfortunately the website hasn't been updated since 2008 and online booking is not possible anymore, time tables are subject to change ; the best way is to ask for information at the train station itself. The network in the north is dense. You can reach Algeria by train from Tunisia, although you will have to change the train at the border post. All border points with Morocco are currently closed.
If you can try to catch the newer trains they are more comfortable and climate-controlled.
By car
The realistic and most secure way to reach Algeria by car is across the Tunisian border.The Mauritanian and Malian borders present some security problems, and the Moroccan border is closed.Note that, if you want to get into Algeria from Niger or from the Tozeur border post in southern Tunisia, you'll have to contract an official guide to accompany you across the Saharan routes; otherwise, police will not allow you to get into Algeria with your car.There are no problems if you want to get into Algeria from the Tunisian border posts in the north. As of May 2012 the border to Morocco is still closed but scheduled to be reopened in July 2012.