Welcome
This is how you say 'You're welcome' in response to 'Thank you'. This is a completely different context from welcoming someone to a place.
Use these variations of 'Bienvenido' to match the gender and number of the person/people you are welcoming. 'Bienvenida' (feminine singular), 'Bienvenidos' (masculine/mixed plural), 'Bienvenidas' (feminine plural).
A common and polite way to say 'Come in' when welcoming someone into your home or office. 'Pase' is slightly more common in this context.
Welcome to my house!
Hello, ladies. Welcome!
Welcome to Mexico! We hope you enjoy your trip.
A: Thank you very much for the help. B: You're welcome, with pleasure.
The biggest point of confusion for learners is that 'welcome' has two meanings in English. 'Bienvenido' is for welcoming someone to a place (an arrival). 'De nada' is for responding to 'thank you' ('you're welcome'). This is true across the entire Spanish-speaking world.
In addition to the standard phrases, when inviting someone into your home, it's very common to hear the friendly and informal command, 'Pásale', which means 'Come on in.'
While 'De nada' is perfectly understood, it is extremely common to hear 'Con gusto' ('With pleasure') as the default response to 'Gracias'.
Due to the use of 'voseo', the informal command to 'come in' is 'Pasá' instead of the 'Pasa' you might hear in other countries.
The vocabulary is the same. The main difference is pronunciation. When saying 'De nada' in response to 'Gracias', the 'c' in 'gracias' is pronounced with a 'th' sound in most of Spain.
Using 'Bienvenido' to mean 'You're welcome'. WRONG: A: Gracias. B: ¡Bienvenido! CORRECT: A: Gracias. B: De nada. 'Bienvenido' is ONLY for arrivals.
Forgetting to match the gender and number. WRONG: ¡Bienvenido, María! CORRECT: ¡Bienvenida, María! The ending must change to '-a' for a female, '-os' for a masculine/mixed group, and '-as' for a female group.
Pronouncing the 'v' like an English 'v'. In Spanish, the 'b' and 'v' have the same sound, which is like an English 'b'. So, it's 'byen-beh-NEE-doh', not 'byen-veh-NEE-doh'.