"DDL" is the abbreviation of "deadline", which means deadline, and usually refers to the deadline for college students to submit their homework. This vocabulary is very popular with college students, because it concisely and clearly expresses their sense of urgency and efforts to complete their homework when facing the deadline of homework.
Every final week, all kinds of final homework come one after another, and catching up with DDL has become a hot topic for college students. The common way for college students to deal with DDL is to stay up late.