Safety is paramount in every game. The aim of the experience is to have fun and this is near impossible if you aren't feeling comfortable.
TTRPGs often include violence and blood, and can include topics and themes that some may find distressing. For example, themes of body autonomy in a Vampire the Masquerade game or endangerment of children in a Call of Cthulu game.
However, your games will always have tools in place to protect everyone at the table and ensure everyone can enjoy themselves.
In games run by myself, some or all of the following tools are used:
The X-Card, designed by John Stavropoulos, is a card with an X on it. Players (or the GM, in some cases) can literally raise this card up to signal they are uncomfortable. Alternatively, this can sit in front of each player or in the middle of the table and a player can tap it. When someone 'plays the x-card', the current action or description fully stops, is decreased in intensity, or focus is moved away from it.
Lines and Veils, designed by Ron Edwards, is a model where everyone at the table can communicate what they don't want in a game. A 'line' is an absolute no go. A 'veil' is something that can happen 'off-screen' or be alluded to. For example, child murder as a line, that will not be in the game, and child endangerment as a veil, that can be spoken about but not actively occur in game.
Conditions, introduced by April Kit Walsh* are an addition to lines and veils for topics or scenarios that may be brought up, if certain conditions are met. For example, systemic bigotry, but only if this is shown as a negative and not acceptable.
The Open Door, designed by Eirik Fatland, is a policy where players are welcome to leave if at any point they feel the need to and will not be judged for doing so.
RPG Consent Checklist, popularised in Monte Cook Games' Consent in Gaming is a simple checklist of potentially triggering topics. Each player can check each item as green, yellow or red. Green is enthusiastic consent/having no problem with this content in games. Yellow signals uncertainty, that it can arise if there is a discussion beforehand or it can happen 'off-screen'. Red is an absolute 'no'. The whole booklet, including the checklist, is available here for free.
Please see the Game-Master agreement here for all the terms I will follow as your GM. Safety for the players and myself is always the priority, and I can promise to do everything I can to ensure it.
*April Kit Walsh describes 'Conditions' in the sourcebook for Thirsty Sword Lesbians. I cannot find this tool anywhere else. It is possible she is not the original designer of it, but I have no reason to believe that.