There are four kinds of Mental Clinging:

The Blessed Buddha once said:
Bhikkhus: There are these four kinds of Clinging. What four?

1: Clinging to Sense-Pleasures...
2: Clinging to Various Views...
3: Clinging to Rituals and Superstition...
4: Clinging to an Ego-Concept...

These are the four kinds of Clinging!
This Noble 8-fold Way is to be developed for the direct experience of the
four kinds of clinging, for the full und
erstanding of these types of clinging,
for their complete elimination, and for their final overcoming, abandoning
and leaving all behind...
The Noble 8-fold Way is
to be developed for the ceasing of all clinging!

1: The 1st kind of clinging to sights, sounds, smells, flavours, touches, and
thoughts is fairly obvious, yet still long habituated and thus tenacious...
2: Clinging is to Views is thinking: Doing good deeds are completely useless.
Doing evil has no consequences! No action has any effect on my future!
3: Clinging to rituals & superstition is like thinking that fire, bathing, and
various empty rituals, like wearing funny hats & praying, can purify mind...
3: Clinging to an Ego-concept, personality-belief, & a 'self' is the assuming
an unchanging internal entity 'I-Me', which however is non-existent...
The proximate cause of all clinging is Craving, which has to be left!
This is the 2nd Noble Truth!
Clinging means: adhering, attaching, gripping,
clasping, clutching, and
grasping, to which we stick stubbornly and tenaciously.

The word pali word The Buddha used 'Upādāna'  literally means 'taking up'
indicating that, as soon as one takes up the object, then clinging occurs!

Sariputta once said:
When, friends, a Noble Disciple understands clinging, the cause of clinging,
the ceasing of clinging, and the way leading to the ceasing of clinging, in
that way he is one of right view, whose view is straight, who has perfect
confidence in the Dhamma, and has arrived at this true Dhamma...
And what is clinging, what is the cause of clinging, what is the ceasing of
clinging, what is the way to the cease clinging?
Friends: There are these 4 kinds of clinging: clinging to sense-pleasures,
clinging to views, clinging to rituals & superstition, and the subtle clinging
to the ego-concept of an assumed inner self. With the arising of craving,
clinging also arises. With the ceasing of craving, clinging thus ceases too!
The way leading to the ceasing of clinging is just this Noble 8-fold Way:
Right View, Right, Motivation, Right Speech, Right Action, Right Livelihood,
Right Effort, Right Awareness, and Right Concentration...

Source: Majjhima Nikāya 9. Sammaditthi Sutta: Discourse on Right View

More on Clinging (Upādanā): An intensified quite painful form of craving.
What are the 5 Clusters of Clinging, Cool Calm, Stilling_of_Clinging,
Clinging_to_the_notion_I_Am, Quenched,

Good Dhamma talk by Ven. Thanissaro Bhikkhu on Clinging:!%20Dependent%20Co-arising.mp3

Source (edited extract):
The Grouped Sayings of the Buddha. Samyutta Nikāya.
Book [V:59] section 45: The Way. 173: The 4 Clingings ...

The 4 Clingings!