Common table expression is a view that exists for a single query

Here’s an example

WITH "average_book_ratings" AS (
    SELECT "book_id", "title", "year", ROUND(AVG("rating"), 2) AS "rating" FROM "ratings"
    JOIN "books" ON "ratings"."book_id" = "books"."id"
    GROUP BY "book_id"
)
SELECT "year" ROUND(AVG("rating"), 2) AS "rating" FROM "average_book_ratings"
GROUP BY "year";

this first bit in the WITH is the CTE defining a view called average_book_ratings, which you then query like any other table or view. Once the query has been run, that thing disappears.