Hold mig opdateret.

Hold is the imperative form of at holde.
That means it is used for giving a command, request, or instruction.

So:

• at holde = the infinitive, to keep / to hold
• hold! = keep! / hold!

In Hold mig opdateret, the speaker is telling someone to do something: keep me updated.

Because mig is the object form of the pronoun jeg.

Compare:

• jeg = I
• mig = me

In this sentence, the speaker is receiving the action, so Danish uses mig:

• Hold mig opdateret = Keep me updated

Just like in English, you would not say Keep I updated.

It is related, but in this sentence it works more like keep than physical hold.

Danish holde has several meanings depending on context, including:

• hold
• keep
• maintain
• sometimes stop in other expressions

In Hold mig opdateret, the idea is keep me in an updated state.

So this is a very natural Danish use of holde, even though the most literal English-looking word would be hold.

Opdateret is the past participle of opdatere, and here it is used like an adjective.

So:

• at opdatere = to update
• opdateret = updated

The structure is basically:

• Hold = keep
• mig = me
• opdateret = updated

So the pattern is similar to English keep someone informed / updated / ready.

Yes. In this sentence, opdateret describes the state that the speaker should remain in.

So grammatically, it functions like an adjective after holde in this kind of construction:

• Hold døren lukket = Keep the door closed
• Hold dig rolig = Keep calm / Stay calm
• Hold mig opdateret = Keep me updated

This is a common pattern in Danish.

Yes, it is completely natural and very common, especially in everyday speech, work situations, emails, and messages.

It sounds normal in contexts like:

• work updates
• project progress
• travel plans
• personal news

It is neither extremely formal nor extremely casual. It is a standard, useful phrase.

Yes. You can add a phrase with om to say what the updates are about.

For example:

• Hold mig opdateret om situationen = Keep me updated about the situation
• Hold mig opdateret om projektet = Keep me updated about the project
• Hold mig opdateret om, hvad der sker = Keep me updated about what is happening

So om often works like about / on here.

Yes, there is a small difference.

• Opdater mig = Update me
• Hold mig opdateret = Keep me updated

Opdater mig can sound like give me an update now.
Hold mig opdateret suggests an ongoing process: continue to keep me informed as things develop.

So if you want regular news over time, Hold mig opdateret is often the better choice.

Yes. Some close alternatives are:

• Hold mig orienteret = Keep me informed
• Hold mig underrettet = Keep me informed; often a bit more formal
• Giv mig besked = Let me know
• Sig til = Let me know / say something when needed

The differences are mostly about tone:

• opdateret sounds modern and very common
• orienteret is also common and slightly more formal
• underrettet can sound more formal or official

A careful approximate pronunciation is:

op-da-TE-ret

A rough English-friendly guide might be:

ob-da-TAIR-eth

A few helpful points:

• the stress is mainly on -te-
• the d in Danish is often softer than English d
• the final -et is not pronounced like English it, but more like a soft eth / uhth sound depending on accent

If you are learning pronunciation, it is best to listen to native audio, because Danish vowel quality and soft consonants are hard to guess from spelling alone.

In imperatives, Danish usually leaves out the subject, just like English often does.

So instead of saying:

• Du, hold mig opdateret

Danish normally just says:

• Hold mig opdateret

The subject is understood as you.

You can add a name or pronoun for emphasis in speech, but the normal form is without it.

No. Behold in Danish is not the normal word here.

The natural phrase is:

• Hold mig opdateret

Even if English learners try to build the sentence more literally, Danish strongly prefers holde in this structure.

So this is one of those expressions that is best learned as a set phrase.