Paris trains simplified

The Seat61 website ( https://www.seat61.com/France-trains.htm ) is the source of info on just about everything train-related. Skim through that section on France to learn the answers to questions you didn't even know you had.

Rick does a good job of providing key information about public transportation in each of his guidebooks.

For a quick look at schedules, I find the Deutsche Bahn website ( https://www.bahn.com/en/view/index.shtml ) the easiest to use, but it will not give you the cost of internal French trains, nor can you buy tickets from the DB.

The SNCF website ( https://en.oui.sncf/en/?prex=T_LSP_524DA5A13173C&s_kwcid=AL!453!3!259797136719!e!!g!!sncf&ef_id=WY35lwAAAFY-fWSC:20180829060619:s&ectrans=1#/ ) will allow you to purchase tickets, or you can use trainline.eu . In either case, be sure you understand the fare rules. On fast trains, if you opt for a low, promo-priced ticket, you are buying something that is non-changeable and non-refundable, so you must be absolutely certain of your plans before making the purchase.

For Versailles, RER-C. Buy tickets on the day of travel. See Parisbytrain.com to find RER-C station closest to you.

For Bayeux, SNCF. Buy tickets online in advance for lower fare. Gare St Lazare

or do you have more general confusion, for example about the Métro?

Are you talking about trains IN Paris, or trains from Paris to other places?

For IN Paris, it is simple. There is the métro, and the RER, but you can count them as one system.
The métro has numbered lines, 1, 2, 3 etc. The RER is an express system, lines A, B, C etc.
See the métro+RER map here: https://www.ratp.fr/sites/default/files/plans-lignes/Plans-essentiels/Plan-Metro.1496264586.pdf

Everything is signposted according to the name of the station at the end of the line, for example "ligne 9 direction Pont de Sèvres". You just need to know which line you want, and which direction. For changing trains, follow "Correspondance" signs.
Click for photo, and another photo.
"Sortie" is exit, with the name of the street you are exiting to.

For tickets, the simplest option is a "t+" ticket, available at machines at all stations, in singles or discounted "Carnet" of 10 tickets. This is valid for 1 trip anywhere in Paris, métro or RER, including changing lines.

Versailles is reachable by RER line C, you pay a higher fare as Versailles is outside Paris city.
For the rest of France, read the aforementioned "Man in Sear 61" page: https://www.seat61.com/France-trains.htm

SNCF runs the trains outside of Paris, so I always buy directly from them (https://www.sncf.com/en). However, they don't always post all available trains ahead of time. For example, if you are several months out, they may not show the direct trains to Bayeux, but as you get closer they start to list them.

You can find various YouTube clips on arriving at CDG and how to get through customs, pick up the RER, or Roissy Bus etc. as well as Gare Nord, Gare Montparnasse, as well as using the Metro. I find it reduces anxiety by actually seeing what to expect at any of these hubs of transportation or many destinations.

I haven't had any trouble buying direct from SCNF. It pops up with a number of trains that fit your search. It's probably good to have it show more earlier and/or later. Some trains to Bayeux are direct but not all. It will save time and hassle if you pick a train that will take you all the way there without changes.

Ok I think I understand the metro & RER, what is the tvg & Eurostar? I’m sorry I’m sure I sound completely ignorant but we don’t have a train system or much public transportation here in TX so I’m completely clueless. Thank you for all your answers so far.

TGV = Train à Grande Vitesse = High Speed Train. This is the brand name SNCF uses for their high speed trains.

SNCF = Société nationale des chemins de fer français = French National Railway Company. They operate most (but not all) of the trains in France, including TGV's. Notable exception is the métro networks in Paris and other big cities. Website: https://ch.oui.sncf/en/

RATP = Régie Autonome des Transports Parisiens = Paris Independant Transport Authority. They operate the métro, trams and buses in Paris. Website: https://www.ratp.fr/en

Eurostar = The company (and brand name) for the high speed trains from London to Paris and Brussels. Website: https://www.eurostar.com/

Thalys = The company (and brand name) for the high speed trains Paris - Brussels - Amsterdam. Website: https://www.thalys.com/

Hope this helps.

Also, since you are going to Bayeux:

Intercités - Long-distance SNCF express trains on routes that haven't been upgraded for the very fast TGVs. Like TGVs, more expensive if you book on the day compared to advance fares, seat reservations included in the ticket.

TER - "Transport express régional" - Most short or medium-distance trains in France outside big cities, the "express" is often misleading. Can be booked in advance if you want to save time at the station, but no discounts and no seat reservations.

Since this is your first time in Paris, you might reconsider spending so much time traveling. Bayeux especially is a lengthy add-on.

To all of the above I suggest as well, tomsguidetoparis.com and parisbytrain.com

I was also going to suggest Paris By Train as there's a LOT of good information there.

A few important points to note. Many visitors just buy a Carnet (10) of t+ tickets. Those have to be inserted in the turnstile to access the platforms and it's very important that you retain those tickets until you exit the Metro system. Failure to retain tickets may result in hefty fines collected on the spot! I don't know how current this is - https://www.ratp.fr/en/categorie-faq/4761 .

For the trip to Versailles, just go to a ticket office and buy a return ticket. Depending on where your hotel is, you may have to use the Metro to reach a connection point for the RER. As I recall, the tickets to Versailles have to be validated (time & date stamped).

Once you're familiar with the Metro, it's very easy to use. If making connections, it's important to note the direction of your next train as there will be different stairways in some cases. If you'll be travelling with a smartphone, there are some great Apps available that will provide specific directions.