"• Let's suppose I'm in a group of friends that most of them are older than me, and when I have to talk to them I use 저 with 요 endings, since we are friends and I respect them; But we are all brazilians practising korean, so I was wondering if that sounds natural. Is 저+요 still 존댓말? Should I use 나 + 요 from now on? • The usage of 반말... Can I use it with my parents and old sister, for example? And to those friends that I mentioned as well? HAHA really confused here!" Yes, 저+요 is still 존댓말. 나+요 is above 반말 but below 저+요. 반말 is dropping the 요 and using other endings that are/can be informal (e.g. 네(요)) Which levels of speech you use with an individual all depends on your relationship to that person. It's not a simple matter of being friends or family. It depends on your actual relationship and connection to that person, as well as their status relative to yours. For example, some people will use 반말 with their grandparents/elders, while others would never imagine doing that and use 존댓말 instead. So only you and your parents could decide which level of speech is most appropriate and you are most comfortable with. The same thing applies to your siblings and friends. I don't know your relationship with each of your Brazilian friends, so I could not tell you. I would probably stick with a 요 ending though if they're older or you're not super close. Here's more information: http://www.talktomeinkorean.com/lessons/level-3-lesson-27/ http://atkmagazine.com/2013/08/02/polite-vs-informal-and-deferential-style/ Don't stress! Just practice with native Korean speakers sometimes too and get feedback. You could even write notebook entries in the style of dialogues to set up a scenario or situation you would encounter in real life.

저 can be used naturally with ㅂ니다/습니다 and 아/어/여요 (or other endings from those respective levels of speech). 나 can be used naturally with 아/어/여요 and 아/어/여 (or other endings from those respective levels of speech, including (이)야). 저 can not be used with 아/어/여 (or other endings from that level of speech). 저, by its very nature, is humble and shows more respect than 나. Therefore, it cannot be used with 반말 ("half-speech"). 나 can not be used with ㅂ니다/습니다 (or other endings from that level of speech). 나, by its very nature, is casual and not as respectful as 저. Therefore, it cannot be used with 존댓말. __ Hope this helps! Please let me know if you have any other questions~