The system is managed by the Helsinki Regional Transport Authority (HSL) and operations are contracted out to VR at least until 2031.

[4] The system operates on four railway lines and comprises 13 services, all of which terminate at Helsinki Central Station.

Within the HSL region, tickets and timetables are fully integrated with other modes of public transport.

[6] Commuter rail is a backbone of public transport in Helsinki and is by far the lengthiest rapid transit system in Finland, carrying a total of around 70 million passengers in 2018[3] and operating around a thousand departures each weekday (2023).

[7] The Coastal Line, completed in 1903, was designed and routed with local travel in mind which has since caused issues for operating long-distance trains.

The construction of housing near stations began quickly and by 1910, the number of daily services had increased to ten.

The Great Depression decreased commuter numbers drastically – at its lowest, only 3 million trips were made per year in the 1930s.

Massive war reparations for the Soviet Union meant that the Finnish state was left with little to no resources for even regular maintenance of the country's railway lines.

The age of the modern Finnish commuter train began in 1969 as the first stretch of the Coastal Line up to Kirkkonummi station was electrified.

Early in the decade, the term commuter train (Finnish: lähijuna) was first adopted into official use.

Letters of the alphabet were introduced as service identifiers in 1972, as inspired by the Copenhagen S-train network.

The initial letters A, H, K, L, N, P, R, S and T were chosen deliberately to function as mnemonic devices and to minimize the risk of ambiguity between each other.

The Martinlaakso Line, opened four years later, was the first rail branch in Finland meant exclusively for commuter trains and has been a backbone for urbanization of the city of Vantaa.

For a short period of time in the 1970s, the letter A was designated to a stopping train to Kirkkonummi station.

These services were instated in their current forms in 2015, after the completion of the Ring Rail Line, and have run on 10 to 20 minute intervals throughout the day ever since.

Often heavily crowded during peak hours, especially in the HSL region, most R departures are operated with up to four Class Sm4 units.

The extended Z route from Helsinki to Kouvola is the longest haul on the entire VR commuter rail network.

The Z was the first Finnish commuter service to regularly require rolling stock capable of running at a speed of 160 km/h.

The line had six services a day in both directions and it was the only train with letter designation on the Helsinki–Riihimäki route that did not stop at Tikkurila.

It was abolished in 2011 in order to improve management of traffic and timetable keeping on the Main Line especially during winter conditions.

Several stops (listed above in parentheses) were procedurally closed in 1990–98 due to low passenger numbers and the H trains disturbing other traffic by being too slow.

The S train was abolished in March 2016 when two small stops located between Kauklahti and Masala and served only by the U-line were closed and the U line now runs twice an hour.

Since 2017, all services within the HSL region have been operated with a fleet of 81 Stadler FLIRT trainsets manufactured between 2008 and 2017, designated as Class Sm5.

In a unique structure of ownership and management, the Class Sm5 trains are owned by neither HSL as the authority or VR as the operator.

Instead, to make the purchase of new modern trainsets possible, a holding company called Pääkaupunkiseudun junakalusto [fi] was established by the four cities forming the Helsinki capital region.

Under direct ownership of said cities, JKOY is a fully independent rolling stock corporation capable of leasing trainsets to any train operator when necessary.