Employer match
Money your employer adds to your retirement plan when you contribute, up to a set percentage of your pay.
A common formula is 50% of what you put in, up to 6% of your salary. Another is 100% up to 3% or 4%. To get the full match, you need to contribute at least the percentage the formula names. Skipping it leaves part of your pay on the table.
Matching money may come with a vesting schedule. It does not count toward your own $24,500 contribution limit.
Example
On a $60,000 salary with a 50% match up to 6%: you contribute $60,000 × 6% = $3,600, and your employer adds $3,600 × 50% = $1,800.