And So On And So Forth

While the abbreviations etc. and et al. are related, they really shouldn't be used interchangeably.

The abbreviation etc. (from the Latin et cetera) means "and so on."  Etc. is most commonly used in informal or technical writing to suggest the logical continuation of a list.

The abbreviation et al. (from the Latin et alii) means "and others."  Et al. is most commonly used in bibliographic citations and in informal or technical writing to suggest the logical continuation of a list of people (not, as a general rule, of things).

Don’t go overboard in trying to make your list or series of people too exhaustive by using redundant phrases and etc. or and et al.

Examples:

· Together the conference attendees participated in plenary sessions, breakout sessions, group activities, teambuilding exercises, networking, etc.
· Ambrose et al. (2016, p. 510) refer to this form of information as "useful thinking.”
· "I know how the song goes.  In fact, not only do Donner, Blitzen, et al., not love him and laugh out loud with glee, but they doubly despise the bulbous-nosed little wimp." (Kelsey Grammer as Dr. Frasier Crane in Cheers, 1986)

Closing thought on the subject:
"Et cetera: the expression that makes people think you know more than you do." (Herbert Prochnow)