What is Repository

Repository is just like EntityManager but its operations are limited to a concrete entity.

You can access repository via getRepository(Entity), Connection#getRepository, or EntityManager#getRepository. Example:

import {getRepository} from "typeorm";
import {User} from "./entity/User";

const userRepository = getRepository(User); // you can also get it via getConnection().getRepository() or getManager().getRepository()
const user = await userRepository.findOne(1);
user.name = "Umed";
await userRepository.save(user);

There are 3 types of repositories:

Repository - Regular repository for any entity.
TreeRepository - Repository, extensions of Repository used for tree-entities (like entities marked with @Tree decorator). Has special methods to work with tree structures.
MongoRepository - Repository with special functions used only with MongoDB.