I'm not a native English speaker, but in Portuguese there are words with the same differences, so I'll try to answer. TALK: if person A *talks* to person B, they are in a dialog. They're having a conversation. One speaks and the other replies, and so on. SPEAK: *speaking* is one of the ways of using language: we can speak, write, listen, read... If we say "someone speaks", that indicates that he/she broke the silence, or that he/she is able to speak... for example, "Speech-impaired people can't speak." "The boss wants to speak with you." SAY: *say* is similar to "speak", but you have to specify what the person speaks. If you use the verb say, you must indicate *what* the subject of the sentence is saying. Example: "I said that... [something]" "He said he didn't like this color." TELL: this means to communicate some information or some fact. "I told you not to do that!" "Tell me... how long have you been living here?" I hope I didn't confuse you.