machine learning - How to know if model is overfitting or underfitting? - Cross Validated

I understand that using cross validation we can validate our model, but it is also possible that maybe our model is underfitting; hence, providing wrong results. One possibility that I can think of

Overfitting and Underfitting with a real-life example - Shiksha Online

a) Examples of underfitting, appropriate-fitting, and over-fitting

I tried a bunch of things: The dangers of unexpected overfitting

Overfitting vs Underfitting in Machine Learning [Differences]

Overfitting and Underfitting in Machine Learning

Overfitting in Machine Learning and Computer Vision

Overfitting in Machine Learning

Overfitting in Machine Learning: What It Is and How to Prevent It

Overfitting and Underfitting in Machine Learning

Underfitting and Overfitting in Machine Learning