For new hams reading this, here's how the callsign process actually works when you get licensed. Each amateur station gets a unique call sign assigned sequentially using the sequential call sign system, based on the alphabetized regional-group list for your operator class and mailing address. When you earn your first license you'll be issued a sequential call sign based on your region and license class group.

A vanity call sign is one assigned by the FCC to replace your existing call sign - but newly licensed individuals cannot get a vanity call as their first call sign. You have to get your initial sequential assignment first, then apply for vanity later if desired.

Good explanation! There's now a $35 charge for vanity applications that used to be free, so new hams should think carefully about whether they really want to change from their sequential assignment.

You can request a new sequential call sign at no extra cost when upgrading your license class or during renewal every 10 years. That might be a better option than paying for vanity if you just want something different.

The sequential system means call signs are assigned sequentially from the pool - so if you don't like your assignment, upgrading license class gets you a new roll of the dice essentially. I upgraded from Tech to General partly for this reason!