A trailer has many pros from a creative standpoint. IT forces you to identify WHO you are talking to and what can you say to get them to listen to your podcast. 

For me, a trailer is 30,60, 90 seconds. When you mark your episode as a trailer it is stuck at the top of your show in Amazon, Spotify, and Apple. Some podcasts do trailer episodes that are 2-5 minutes long.

As always in podcasting, there are no set rules.

The different types of trailers

When do you know if your trailer is good?

What do you say in a trailer?

Where do you post this? How do you use it?

My Spouse Has Dementia

Love Thy Lawyer

Your Podcast Consultant

Branden Ushio at the Geek Nerd Network

Ask the Podcast Coach Episode 380

Big Seance Podcast (Trailer by Music Radio Creative)

The Trojan Horse Affair

Question of the Month (Deadline /25/22)

Podcast Promo Show

 Cooler Websites (Domain and Web Hosting)

14:04: Join the School of Podcasting

 The Voice in My Head (Neil Hed)