user-1: Can you quickly explain "everything is impermanent"? Is it metaphysical or ontological claim, that nothing that "exists" will exist forever?
Or is it a claim that nothing can always be (meaning having that nature, rather than 'exist') anything? If not that latter, does Buddhism universally agree that there is no awareness of something being what it is, without existence?

Can I be aware of, for example, a shape being red without existence and "permanently" in the standard way of using that word, even if "everything is impermanent"?

user471: Anicca according to wisdomlib means:

anicca : (adj.) not stable; impermanent.
(Source): BuddhaSasana: Concise Pali-English Dictionary

From the AccessToInsight Glossary for A:

anicca: Inconstant; unsteady; impermanent.

This is elaborated by the Buddha in DN 17 (translated by Bhikkhu Sujato):

See, Ānanda! All those conditioned phenomena have passed, ceased, and
perished.
So impermanent are conditions,
Evaṃ aniccā kho, ānanda, saṅkhārā;
so unstable are conditions,
evaṃ addhuvā kho, ānanda, saṅkhārā;
so unreliable are conditions.
evaṃ anassāsikā kho, ānanda, saṅkhārā.
This is quite enough for you to become disillusioned, dispassionate,
and freed regarding all conditions.
DN 17

You may be happy and confident today, based on your close-knit family, dependable friends, good looks, fantastic health, abundant wealth, productive career or business etc. But all these will not last forever. They are impermanent (aniccā), unstable (addhuvā) and unreliable (anassāsikā). To peg your happiness or sense of self to these things will bring suffering. That's the relationship of impermanence to suffering. Also see SN 22.93 below.
The purpose of seeing conditioned things as impermanent, unstable and unreliable, is so that you can become disillusioned, dispassionate and free from clinging.
It's not metaphysics or ontology. It's pragmatism and methodological.

“Suppose, mendicants, there was a mountain river that flowed swiftly,
going far, carrying all before it. If wild sugarcane, kusa grass,
reeds, vetiver, or trees grew on either bank, they’d overhang the
river. And if a person who was being swept along by the current
grabbed the wild sugarcane, kusa grass, reeds, vetiver, or trees, it’d
break off, and they’d come to ruin because of that.
In the same way, an uneducated ordinary person has not seen the noble
ones, and is neither skilled nor trained in the teaching of the noble
ones. They’ve not seen good persons, and are neither skilled nor
trained in the teaching of the good persons.
They regard form as self, self as having form, form in self, or self
in form. But their form breaks off, and they come to ruin because of
that. They regard feeling … perception … choices … consciousness as
self, self as having consciousness, consciousness in self, or self in
consciousness. But their consciousness breaks off, and they come to
ruin because of that.
What do you think, mendicants? Is form permanent or impermanent?”
“Impermanent, sir.” …
“Is feeling … perception … choices … consciousness permanent or
impermanent?”
“Impermanent, sir.”
“So you should truly see … Seeing this … They understand: ‘… there is
no return to any state of existence.’”
SN 22.93


user13709: A red square will always be a red square. The term "red" defines a certain frequency range. The term "square" defines a certain geometrical relationship.  These are abstractions which we use to name what we see. So "red square" is a name.
Yet when we see a red square, we actually see only a form that matches the name "red square".  And these forms, such as a printed or painted red square are impermanent. The printing or painting of a red square is always impermanent. Printings and paintings fade and crumble away with time.
So we can talk and talk about red squares forever. But all that we see as a red square will crumble away. These perceived forms are impermanent. Understanding that these forms are impermanent leads us to question our restless grasping for such forms (as in "that's MY red square!").

SN22.157:1.10: Is form permanent or impermanent?”
SN22.157:1.11: “Impermanent, sir.” …
SN22.157:1.13: “But by not grasping what’s impermanent, suffering, and perishable, would fetters, insistence, and shackles arise?”

Names are intangible. Forms are tangible yet unsatisfactorily impermanent. Grasping and holding on to impermanence is suffering.

DN15:3.1: So: name and form are conditions for consciousness. Consciousness is a condition for name and form. Name and form are conditions for contact. Contact is a condition for feeling. Feeling is a condition for craving. Craving is a condition for grasping. Grasping is a condition for continued existence. Continued existence is a condition for rebirth. Rebirth is a condition for old age and death, sorrow, lamentation, pain, sadness, and distress


user254: I think the assertion is that all sankharas are impermanent -- Three marks of existence -- more specifically "all conditioned things".
The idea is that most things are "conditioned" -- they have conditions in which they come into being, or are fabricated -- and they cease when those conditions cease to be.
So "a sight" (for example) is conditioned -- the conditions for seeing are an "eye" plus a "visual object" plus an "internal sense of sight" -- sight arises when these make contact, and any or every sight is impermanent (i.e. when that contact ceases). The same is true for other sense-impressions (including thoughts).
Physical objects are impermanent too, they're created from other things and eventually destroyed.
In summary, "all that arises, ceases".
Conversely whatever is "unconditioned" isn't impermanent.

-1: <p>Can you quickly explain &quot;everything is impermanent&quot;? Is it metaphysical or ontological claim, that nothing that &quot;exists&quot; will exist forever?</p>
<p>Or is it a claim that nothing can always be (meaning having that nature, rather than 'exist') anything? If not that latter, does Buddhism universally agree that there is no <em>awareness</em> of something being what it is, without existence?</p>
<hr />
<p>Can I be aware of, for example, a shape being red without existence and &quot;permanently&quot; in the standard way of using that word, even if &quot;everything is impermanent&quot;?</p>
 471: <p>Anicca according to <a href="https://www.wisdomlib.org/definition/anicca" rel="nofollow noreferrer">wisdomlib</a> means:</p>
<blockquote>
<p>anicca : (adj.) not stable; impermanent.<br />
(Source): BuddhaSasana: Concise Pali-English Dictionary</p>
</blockquote>
<p>From the <a href="https://www.accesstoinsight.org/glossary.html#a" rel="nofollow noreferrer">AccessToInsight Glossary for A</a>:</p>
<blockquote>
<p>anicca: Inconstant; unsteady; impermanent.</p>
</blockquote>
<p>This is elaborated by the Buddha in <a href="https://suttacentral.net/dn17/en/sujato" rel="nofollow noreferrer">DN 17</a> (translated by Bhikkhu Sujato):</p>
<blockquote>
<p>See, Ānanda! All those conditioned phenomena have passed, ceased, and
perished.</p>
<p>So <strong>impermanent</strong> are conditions,<br />
<em>Evaṃ <strong>aniccā</strong> kho, ānanda, saṅkhārā;</em></p>
<p>so <strong>unstable</strong> are conditions,<br />
<em>evaṃ <strong>addhuvā</strong> kho, ānanda, saṅkhārā;</em></p>
<p>so <strong>unreliable</strong> are conditions.<br />
<em>evaṃ <strong>anassāsikā</strong> kho, ānanda, saṅkhārā.</em></p>
<p>This is quite enough for you to become disillusioned, dispassionate,
and freed regarding all conditions.<br />
<a href="https://suttacentral.net/dn17/en/sujato" rel="nofollow noreferrer">DN 17</a></p>
</blockquote>
<p>You may be happy and confident today, based on your close-knit family, dependable friends, good looks, fantastic health, abundant wealth, productive career or business etc. But all these will not last forever. They are impermanent (<em>aniccā</em>), unstable (<em>addhuvā</em>) and unreliable (<em>anassāsikā</em>). To peg your happiness or sense of self to these things will bring suffering. That's the relationship of impermanence to suffering. Also see <a href="https://suttacentral.net/sn22.93/en/sujato" rel="nofollow noreferrer">SN 22.93</a> below.</p>
<p>The purpose of seeing conditioned things as impermanent, unstable and unreliable, is so that you can become disillusioned, dispassionate and free from clinging.</p>
<p>It's not metaphysics or ontology. It's pragmatism and methodological.</p>
<blockquote>
<p>“Suppose, mendicants, there was a mountain river that flowed swiftly,
going far, carrying all before it. If wild sugarcane, kusa grass,
reeds, vetiver, or trees grew on either bank, they’d overhang the
river. And if a person who was being swept along by the current
grabbed the wild sugarcane, kusa grass, reeds, vetiver, or trees, it’d
break off, and they’d come to ruin because of that.</p>
<p>In the same way, an uneducated ordinary person has not seen the noble
ones, and is neither skilled nor trained in the teaching of the noble
ones. They’ve not seen good persons, and are neither skilled nor
trained in the teaching of the good persons.</p>
<p>They regard form as self, self as having form, form in self, or self
in form. But their form breaks off, and they come to ruin because of
that. They regard feeling … perception … choices … consciousness as
self, self as having consciousness, consciousness in self, or self in
consciousness. But their consciousness breaks off, and they come to
ruin because of that.</p>
<p>What do you think, mendicants? Is form permanent or impermanent?”</p>
<p>“Impermanent, sir.” …</p>
<p>“Is feeling … perception … choices … consciousness permanent or
impermanent?”</p>
<p>“Impermanent, sir.”</p>
<p>“So you should truly see … Seeing this … They understand: ‘… there is
no return to any state of existence.’”<br />
<a href="https://suttacentral.net/sn22.93/en/sujato" rel="nofollow noreferrer">SN 22.93</a></p>
</blockquote>
 13709: <p>A red square will always be a red square. The term &quot;red&quot; defines a certain frequency range. The term &quot;square&quot; defines a certain geometrical relationship.  These are abstractions which we use to name what we see. So &quot;red square&quot; is a name.</p>
<p>Yet when we see a red square, we actually see only a form that matches the name &quot;red square&quot;.  And these forms, such as a printed or painted red square are <em>impermanent</em>. The printing or painting of a red square is always impermanent. Printings and paintings fade and crumble away with time.</p>
<p>So we can talk and talk about red squares forever. But all that we <em>see</em> as a red square will crumble away. These perceived forms are impermanent. Understanding that these forms are impermanent leads us to question our restless grasping for such forms (as in &quot;that's MY red square!&quot;).</p>
<blockquote>
<p><a href="https://suttacentral.net/sn22.157/en/sujato#sn22.157:1.10" rel="nofollow noreferrer">SN22.157:1.10</a>: Is form permanent or impermanent?”<br />
<a href="https://suttacentral.net/sn22.157/en/sujato#sn22.157:1.11" rel="nofollow noreferrer">SN22.157:1.11</a>: “Impermanent, sir.” …<br />
<a href="https://suttacentral.net/sn22.157/en/sujato#sn22.157:1.13" rel="nofollow noreferrer">SN22.157:1.13</a>: “But by not grasping what’s impermanent, suffering, and perishable, would fetters, insistence, and shackles arise?”</p>
</blockquote>
<p>Names are intangible. Forms are tangible yet unsatisfactorily impermanent. Grasping and holding on to impermanence is suffering.</p>
<blockquote>
<p><a href="https://suttacentral.net/dn15/en/sujato#dn15:3.1" rel="nofollow noreferrer">DN15:3.1</a>: So: name and form are conditions for consciousness. Consciousness is a condition for name and form. Name and form are conditions for contact. Contact is a condition for feeling. Feeling is a condition for craving. Craving is a condition for grasping. Grasping is a condition for continued existence. Continued existence is a condition for rebirth. Rebirth is a condition for old age and death, sorrow, lamentation, pain, sadness, and distress</p>
</blockquote>
 254: <p>I think the assertion is that all <em>sankharas</em> are impermanent -- <a href="https://en.wikipedia.org/wiki/Three_marks_of_existence#Description" rel="nofollow noreferrer">Three marks of existence</a> -- more specifically &quot;all <em>conditioned</em> things&quot;.</p>
<p>The idea is that most things are &quot;conditioned&quot; -- they have conditions in which they come into being, or are fabricated -- and they cease when those conditions cease to be.</p>
<p>So &quot;a sight&quot; (for example) is conditioned -- the conditions for seeing are an &quot;eye&quot; plus a &quot;visual object&quot; plus an &quot;internal sense of sight&quot; -- sight arises when these make contact, and any or every sight is impermanent (i.e. when that contact ceases). The same is true for other sense-impressions (including thoughts).</p>
<p>Physical objects are impermanent too, they're created from other things and eventually destroyed.</p>
<p>In summary, &quot;all that arises, ceases&quot;.</p>
<p>Conversely whatever is &quot;unconditioned&quot; isn't impermanent.</p>
