RMT (Rail, Maritime and Transport union) and ASLEF (The Associated Society of Locomotive Engineers and Firemen) members are striking in an ongoing dispute over pay and conditions.

ASLEF represents drivers, whereas RMT represents members from lots of different sectors within the rail industry - including station staff and guards.

When ASLEF members go on strike, it usually means there are no drivers. When RMT members go on strike, there is widespread disruption to the network with lots of people in different roles going on strike.

Here is everything you need to know:

Who is walking out and when?

RMT members working on the London Underground will strike in September and October.

This involves thousands of Tube staff and means underground services in the capital will be completely shut down on these dates:

Wednesday 4 October

Friday 6 October

ASLEF train drivers at rail networks across the country are set to strike on these dates:

Saturday 30 September

Wednesday 4 October

There will also be an ASLEF overtime ban - an action short of a strike - on the following days across the UK rail network:

Friday 29 September

Monday 2 October

Tuesday 3 October

Wednesday 4 October - when there is already a strike in place

Thursday 5 October

Friday 6 October

A number of rail services will be affected on these days, albeit not as dramatically as on all-out strike dates.

Which rail lines and networks will be affected - and how?

London Underground

Tube services will be "severely affected" or not run at all on 4 October and 6 October. There will also be no night tube on 6 October.

There will be disruption before 8am the day after strikes on 5 October and 7 October.

The Elizabeth Line, London Overground and tram services are not affected.

Avanti West Coast

Avanti West Coast will not be operating any services on Saturday 30 September or Wednesday 4 October.

Customers who booked tickets to travel on these days can claim a full, fee-free refund from their point of purchase.

Customers with pre-booked tickets for travel on a strike day can use their ticket the day before or the two days after.

Avanti plans to run its normal timetable during overtime bans, but recommends you check before you travel as the impact will vary from route to route.

C2C

There will be no C2C service on Saturday 30 September and Wednesday 4 October.

On days when overtime bans are in place, there will be a reduced peak time service and a reduced frequency of two trains per hour during off-peak hours across all routes.

First and last trains will be unaffected.

Chiltern Railways

There will be no Chiltern Railways services on Saturday 30 September or Wednesday 4 October on any routes.

There will also be a "slightly reduced" service on Friday 29 September in preparation for the planned strike day.

Chiltern Railways will be running an amended timetable during the week of overtime bans, which travellers can check here.

CrossCountry

There will be no CrossCountry services on Saturday 30 September and Wednesday 4 October.

Some services will be amended during overtime ban dates. You can view the list of trains affected on each day here.

East Midlands Railway

There will be no East Midlands Railway service on Saturday 30 September and Wednesday 4 October.

East Midlands says its journey planners have now been updated for days where an overtime ban is in place. Check here for updates.

GTR

GTR, also known as Govia Thameslink Railway, is the UK's biggest railway franchise and operates Southern, Thameslink, Great Northern and Gatwick Express.

It says there will be no Thameslink, Great Northern or Gatwick Express services operating on Saturday 30 September and Wednesday 4 October.

A limited Southern shuttle service will run, calling at Gatwick Airport and London Victoria only.

Services the next day after each strike - Sunday 1 October and Thursday 5 October - will begin much later than normal, with some routes having no services before 7am.

On days when an overtime ban is in place, GTR says an amended timetable with fewer services will run.

The usual non-stop Gatwick Express service between London Victoria, Gatwick Airport and Brighton will not run.

To help customers, extra stops at Clapham Junction and East Croydon have been added, so these trains will be operating as Southern services.

Gatwick Express tickets will be valid on Southern and Thameslink at no additional cost.

Find out more about each of GTR's lines by clicking on their names at the top of this section.

Great Western Railway

Great Western Railway (GWR) will be operating a reduced and revised timetable Saturday 30 September and Wednesday 4 October.

Many parts of the network will have no service at all. Services that go ahead will start from 7.30am and all journeys must be completed by 6.30pm.

GWR says there is likely to be short-notice alterations or cancellations to its services on days when overtime bans are in place.

You can check GWR's website for updates nearer the time.

Greater Anglia and Stansted Express

Reduced services are expected to run on both strike and overtime ban days.

You can click here to see what plans are in place on all affected dates.

Heathrow Express

On the two strike days - 30 September and 4 October - there will be fewer trains going to Heathrow Airport and they will start later and finish earlier.

Trains will run between Paddington and Heathrow between 7.40am and 6.25pm.

Services between Terminal 5 and Paddington will run between 7.42am and 6.57pm.

And there will be trains between 7.47am and 7.02pm from Heathrow Central into Paddington.

The Elizabeth Line will service customers travelling from London to Heathrow.

Heathrow has not announced any changes during overtime bans. Click here for more information about its services.

LNER

LNER services will run on an "extremely limited timetable" during strike days, with minor alterations on days before and after them.

You can find more details here.

London Northwestern Railway

There will be no London Northwestern Railway (LNR) service on Saturday 30 September and Wednesday 4 October.

It will have buses in place of trains between Watford Junction and St Albans Abbey on days when there are overtime bans.

You'll be able to see what impact the overtime ban will have on LNR via journey planners.

Northern

There will be no Northern service in operation on Saturday 30 September and Wednesday 4 October, and no rail replacement bus services.

Days affected by overtime bans are likely to cause some short-notice alterations or cancellations. You can check here for updates.

Southwestern Railway

An extremely limited service will operate on a small number of lines during strike days, and most of the Southwestern Railway mainland network will be closed. There will be no service on the Island Line.

Customers are advised to only travel if absolutely necessary.

Reduced services will operate across the mainland South Western Railway network on overtime ban days, with an hourly service on the Island Line.

Find out more here.

Southeastern

There will be no Southeastern service in operation on any routes on strike days.

Southeastern expects to run a full service during overtime ban periods.

TransPennine

No TransPennine Express service will run on any route during the strikes on Saturday 30 September and Wednesday 4 October.

There will also be some early morning and late evening alterations on the days before or after a strike day.

TransPennine Express plans to run its normal timetable during overtime ban days but warns there could be significant disruption to your journey, so be sure to check before you travel.

West Midlands Railway

There will be no West Midlands Railway service on Saturday 30 September and Wednesday 4 October.

On days when the overtime ban is in place, reduced train services will operate between Birmingham New Street and Hereford and Birmingham New Street and Shrewsbury - and a bus service will replace trains between Nuneaton and Leamington Spa via Coventry.

The overtime bans may lead to amended timetables and on-the-day cancellations, particularly if there is disruption to services, so check before you travel.

How you can remain up-to-date

You can click on any of the links provided above to check for updates on specific lines.

National Rail urges anyone hoping to travel on strike and overtime ban days to use its Journey Planner to keep an eye on how services will be affected.

Any journey accompanied by a yellow warning triangle means the information is still subject to change.

Most journeys should now be up to date on the planner.

If you are planning to travel on Gatwick Express, Great Northern, Southern or Thameslink, journeys on 5 and 6 October will be updated on Friday 29 September.