Age discrimination involves treating someone (an applicant or employee) less favorably because of his or her age. This is true in both hiring and employing.
If you can do the job your age should not prohibit you from obtaining or keeping a job. If your employer is treating you bad or fired you because you are over 40 years of age then you may have a claim for age discrimination.
The Age Discrimination in Employment Act (ADEA) only forbids age discrimination against people who are age 40 or older. It does not protect workers under the age of 40. It is not illegal for an employer to favor an older worker over a younger one, even if both workers are age 40 or older.
Discrimination can occur when the victim and the person who inflicted the discrimination are both over 40.