The difference between 'estas' and ' tienes'
Hi, I've decided to learn a new language and chose Spanish. I've just started and am confused by, when to use ' estas' as opposed to 'tienes'. They seem to be interchangeable! I've looked for differences but I can't tell when to use one over the other. What am I missing here?
2 Answers
Welcome to the forum. I assume you are still a beginner in Spanish and fluent or advanced in English? Can you add your language levels to your profile? If you decide to ask or answer questions this information is helpful.
Is Spanish the first 'foreign' language you have tried learning? Are you self studying or do you go to a class?
It is a good idea to work out how to pronounce Spanish words. Try the BBC programme Mi Vida Loca or try some podcasts starting with beginner eg Notes in Spanish. Estás is the 2nd person singular of estar. Estar means to be. Spanish also uses Ser to mean to be. You will take time to learn all the differences, but ser is used more often than estar.
Tener means to have. There is also a verb haber meaning to have, but that is mainly used to form some verb tenses and usefully in the third person singular [hay] to mean there is or there are
Here is a picture showing the main uses of tener. Some of the phrases are translated into English using to be - eg I am 10 years old - Spanish I 'have' 10 years I am thirsty - Spanish I have thirst.

Now if you go to the front page of this site and put tener or estar in the translate box it will take you to a page with lots of information
Buena suerte
In case you don't "get" the above explanation, it's just that Spanish, French, and Italian, use the verb "to have" instead of "to be" in certain cases.
Explaining Mardle's graphic.
Instead of saying "I am hungry" we say "I have hunger." Tengo hambre
To say "I am 30 years old" we say "I have thirty years. Tengo treinta años
To say that Pedro is hot." (from the weather) we say "Pedro has heat" Pedro tiene calor
Maite is thirsty becomes, "Maite has thrist" Maite tiene sed
Carlos is right. "Carlos has reason" Carlos tiene razón
Carlos is wrong. "Carlos no has reason" Carlos no tiene razón.
However the verbs for to be "Ser and Estar" are also in use. See my article on this link.
It's a good link. You will learn a lot from it.