The adverb still has a number of different uses. It is used for saying that a situation continues to exist up to and including a particular time, especially when this seems surprising, e.g. 'We were still cleaning the house when the guests started to arrive' or 'Is Terry still in college?'
It can also be used to emphasise that a particular situation has not completely ended or changed, as in 'If we have to, we can still request assistance from other authorities'. You can also use still to state that something remains true despite what you have just said or done, e.g. ‘We knew we wouldn’t win the game but it was still exciting’ and ‘This is a short film but it is still too long’.
Sometimes, still can be used in initial position for this purpose, having a similar meaning to however or nevertheless: 'I hadn't seen him for 25 years. Still, I recognised him immediately when I saw him'. With the meaning of even, still can be used with comparative adjectives, as in ‘The freezing weather made our task still more difficult’.
For extra emphasis, inversion can be used: ‘The medical expenses are a massive drain. Worse still, Greg may lose his job’. Used together with more or further, still emphasises that an amount, increase or reduction is even greater than the amount already mentioned: ‘Fuel prices could rise still further in the coming months’.
Finally, still can also be used as a filler in much the same way as anyway. After a pause in the conversation, you might say 'Still, you’ve always got your family and that’s the main thing’.