No te preocupes.

Because preocuparse is commonly used as a pronominal/reflexive-style verb when talking about a person worrying.

• te = yourself / you
• preocuparse = to worry

So no te preocupes is literally something like don’t worry yourself.

In practice, English does not usually say it that way, but Spanish often uses this structure.

Examples:

• Me preocupo = I worry
• Te preocupas = you worry
• No te preocupes = don’t worry

It is often taught as reflexive, but more precisely it is usually treated as a pronominal verb in this meaning.

That means the pronoun is a normal part of how the verb is commonly used when someone is worrying.

Compare:

• Me preocupo = I worry
• Esto me preocupa = this worries me

So Spanish can express the idea in two ways:

1. preocuparse = to worry
   
   • No te preocupes
2. preocupar = to worry someone
   
   • Eso no te preocupa = that does not worry you

This distinction is very common and very useful.

Because negative commands in Spanish use the present subjunctive, not the regular present indicative.

So:

• te preocupas = you worry
• no te preocupes = don’t worry

This is a standard rule:

• Hablas → No hables
• Comes → No comas
• Vives → No vivas
• Te preocupas → No te preocupes

So preocupes appears because this is a negative command.

Because no te preocupa means something different.

• No te preocupa = it does not worry you
• No te preocupes = don’t worry

So:

• preocupa is a statement in the present tense
• preocupes is a negative command

This is an important contrast.

In Spanish, negative commands are formed with no + pronoun + verb.

So:

• No te preocupes
• No me digas
• No lo hagas

With negative commands, object/reflexive pronouns go before the verb.

Compare that with positive commands:

• Preocúpate = worry
• No te preocupes = don’t worry

So the pronoun changes position depending on whether the command is affirmative or negative.

No. That is not correct.

Spanish does not make negative commands by simply putting no in front of the positive command.

• Correct positive command: Preocúpate
• Correct negative command: No te preocupes
• Incorrect: No preocúpate

This is because negative commands require the subjunctive form and the pronoun goes before the verb.

The infinitive is preocuparse.

You can think of the sentence as coming from:

• infinitive: preocuparse
• tú form in the present: te preocupas
• negative command: no te preocupes

If you want the non-pronominal base verb, that is preocupar.

Yes. It is the informal singular form, used with tú.

In Spain, other common versions are:

• No te preocupes = informal singular
• No se preocupe = formal singular
• No os preocupéis = informal plural in Spain
• No se preocupen = formal plural, or general plural in many regions

So if you are speaking to one friend, No te preocupes is perfect.

In Spain, the usual informal plural form is:

• No os preocupéis

This uses vosotros.

Breakdown:

• os = yourselves / you all
• preocupéis = subjunctive form for vosotros

So:

• one person, informal: No te preocupes
• several people, informal in Spain: No os preocupéis

This is especially important if you are learning Spanish from Spain rather than Latin American Spanish.

A simple pronunciation guide is:

noh teh preh-oh-KOO-pehs

A few notes:

• no is a clear noh
• te is teh
• preocupes has four syllables: pre-o-cu-pes
• the stress falls on cu: pre-o-CU-pes

The u is pronounced here, unlike in combinations such as gue or gui.

Because it follows normal Spanish stress rules.

preocupes ends in s, so the stress normally falls on the second-to-last syllable. That is exactly what happens:

• pre-o-CU-pes

Since the stress is regular, no written accent is needed.

By contrast, the positive command preocúpate does have an accent mark:

• pre-o-CÚ-pa-te

That accent is written because adding the pronoun changes where the stress would naturally fall.

Yes, very common. It is one of the most natural everyday ways to tell someone not to worry.

People use it:

• to reassure someone
• to tell someone something is not a problem
• to soften a situation
• to respond kindly after an apology or concern

It is warm, common, and completely normal in Spain.

Usually no. Even though it is grammatically a command, in real use it is often more like reassurance than an order.

Tone matters a lot.

It can sound:

• kind
• comforting
• casual
• friendly

For example, if someone apologizes, saying No te preocupes is often a polite way to put them at ease.

So grammatically it is an imperative, but socially it is very often gentle.

Yes. That is a very common extension.

• No te preocupes por eso = don’t worry about that
• No te preocupes por mí = don’t worry about me
• No te preocupes por nada = don’t worry about anything

So No te preocupes can stand alone, or it can be followed by por + noun/pronoun to say what the worry is about.