The idea for black in the french defense is to undermine whites center as soon as possible. With e6 and e5 black immediately fights for control in the center.
The french defence is covered a lot on YouTube.
For example, Hanging Pawns has a series on the opening with 8 videos. In the series he discusses the main variations of the opening and explains the ideas of the theory in an understandable way.
Ben Finegold also has a lecture on the opening for the Saint Louis Chess Club: Introduction to the French Defence | Kids’ Class
The name of the French defense dates from 1834. In the middle of a correspondence chess competition between a London team and one from Paris, the French responded to the opening move 1. e4, by the Londoners, with the move 1. … e6 and won the game.
Studies about the French Defense
Learn the French Defense using public studies.
French Defence35 by Ja
A study about the French Defense. Going over the important themes and covering multiple sidelines. Created by lichess user Mr_Pennings: https://lichess.org/study/A4EBp7Ds
Rozman French Defense by Gotham Chess28 by alphadave
The Rozman French Defense as studied by IM Levy (GothamChess). Link to the youtube video: https://www.youtube.com/watch?v=vLH1Yw6skaI
Beating the French7 by danwilkins7
The Tarrasch Line to beat the French.
The French Defense - Intro6 by Painterpainter
Intro to the French Defense for Black
French Defense study by Lenin Perez4 by fatewind1
Practicing the variations of Lenin Perez's French Defense study from Lichess.
Play against Stockfish
Do you want to try out the French Defense? Train this opening against Stockfish.
Play against Stockfish either as white or black and explore the opening.