"Daddy issues" is an informal term generally referring to the trouble some people have with forming secure relationships in adulthood, based on an early unhealthy connection or lack thereof with their father.
For what it's worth, it's not a condition listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM–5), and the term is often used as a way to belittle women's struggles and needs. (And by the way, anyone can have a complicated relationship with their father, not just women.)
A more helpful term is simply attachment issues or attachment wounds, which in attachment theory refers to adults who had a troubled relationship with their earliest caregivers and now have difficulty forming secure attachments.
Below, are a few signs you might have "daddy issues," aka attachment issues.
What are daddy issues?
Signs you may have daddy issues
You're only attracted to older men
They're often financially stable, and they appear confident and know exactly what to do. If you've had a complicated relationship with your father, your subconscious may crave a father figure to protect and adore you. You may yearn for an older man to provide the affection you missed in childhood. The problem is that, as with a father/daughter relationship, this pairing may bring an imbalance of power.
You are clingy, jealous, or overprotective
People with insecure relationships with their earliest caregivers often grow up to have an anxious attachment style, meaning you constantly worry that your partner might leave you. You might get jealous frequently and find yourself checking their cellphone, just to make sure they're not cheating.
Importantly, this type of codependency may eventually suffocate your romantic relationships, leaving you a product of your own fears—abandonment! Thus, anyone with "daddy issues" should prioritize learning how to be emotionally independent.
You need constant reassurance of love and affection
You continually compare yourself to their past partners and everyone else on the planet. If you have attachment issues, you may feel insecure with your partner and constantly need assurance that they love you. This can get exhausting, and eventually, the neediness may push them away, which will reinforce your greatest fear—you are unlovable and unwanted.
All the more reason to recognize signs of a codependent relationship early and learn to heal.
You give the impression that you only care about sex
You crave sex. Lots of it. You feel loved when having sex with someone. You sometimes engage in risky behaviors to satisfy your needs. Your self-esteem tends to be based on whether or not someone wants you sexually.
Sometimes we use feeling attractive to others through sex as a proxy for feeling loved and adored, and this can be especially true for people who struggle with attachment issues. Of course, the reality is that sexual connection can exist apart from love, and conflating the two can put you at risk of getting hurt.
You're terrified of being alone
You would rather be in a dysfunctional relationship than be single. You bounce from relationship to relationship and experience all the issues that go with rebound dating and rushing into relationships without giving them time to see if there's compatibility. If you have attachment issues, particularly an anxious attachment style, the fear of being alone may reduce your ability to develop your own unique identity and move forward into a healthy, fulfilling relationship with healthy self-esteem.
You know you've got a complicated relationship with your dad
Was your father absent in your life? Was he physically present but emotionally unavailable? Was your father abusive toward you physically, emotionally, or sexually?
If you said yes to any of the above, that's reason enough to assume you may have attachment issues that require healing.
What to do about it
You can't change your past, but you can change the way you view yourself, your future, and the new people you attract into your life.