¡Buenos días!

In Spain, buenos días is the standard fixed expression for good morning.

A native English speaker often expects a singular noun because English says morning, but Spanish uses the plural días in this greeting. You should learn it as a set phrase.

In Spain, buen día is not the normal greeting. You may hear it in some other Spanish-speaking countries, but buenos días is what you should use for Spain.

Because días is a masculine plural noun, the adjective has to agree with it.

• día = masculine
• plural: días
• adjective in masculine plural: buenos

So:

• buenos días
• buenas tardes
• buenas noches

This is a good example of adjective agreement in Spanish.

This is one of those important exceptions in Spanish.

Most nouns ending in -a are feminine, but el día is masculine:

• el día
• los días

So the greeting is buenos días, not buenas días.

It is used in the morning.

In Spain, it is generally appropriate from early morning until around lunch time / midday. After that, people usually switch to:

• Buenas tardes = good afternoon / good evening
• Buenas noches = good evening / good night

Exact timing can vary a bit by context and region, but buenos días is definitely the standard morning greeting.

It works for both.

You can say ¡Buenos días! to:

• friends
• coworkers
• shop staff
• strangers
• teachers
• older people

It is polite and neutral, so it is one of the safest greetings to use. In Spain, it can sometimes sound a little more polite than just hola, especially with strangers or in customer-service situations.

Yes, in standard Spanish writing, exclamations use both:

• opening exclamation mark: ¡
• closing exclamation mark: !

So the correct written form is:

• ¡Buenos días!

In casual texting, some people may leave out the opening mark, but in correct written Spanish you should include it.

A simple pronunciation guide is:

BWEH-nos DEE-as

A bit more closely:

• buenos = BWEH-nos
• días = DEE-as

A few useful notes:

• The bu in buenos sounds like bwe.
• The í in días is stressed.
• días has two syllables: dí-as.

The accent mark in días shows that the stress falls on the í:

• dí-as

It also helps show that the i and a are pronounced separately rather than merged into one diphthong.

So you say:

• DEE-as

not something like one blended syllable.

Not normally.

On its own, Buenos does not work as a standard greeting. The full expression is:

• Buenos días

In Spain, you may sometimes hear the informal shorthand:

• Buenas

This is a casual shortened greeting, but buenos by itself is not the usual equivalent.

Normally, no. ¡Buenos días! is mainly a greeting when you meet someone, not a farewell.

If you want to say something like have a good day, you would use something else, for example:

• Que tengas un buen día
• Que pase(s) un buen día in some contexts

So think of ¡Buenos días! as hello / good morning, not goodbye.

Usually, no.

In normal Spanish, greetings like buenos días are written in lowercase unless they begin a sentence:

• Buenos días, Ana.
• Le dijo buenos días al entrar.

So the capitals in ¡Buenos días! are because it starts the sentence.

Yes, very naturally.

For example:

• ¡Buenos días, Ana!
• ¡Buenos días, señor!
• ¡Buenos días, profesora!

This is very common in Spain and can sound polite and friendly.

Yes.

In Spain, hola is very common, but buenos días is often preferred when you want to sound:

• more polite
• more respectful
• more appropriate in formal or public settings

For example, when entering:

• a shop
• a doctor’s office
• a classroom
• an office

¡Buenos días! is often the most natural choice.