On Tuesday, 1st August 2017, the endorsement of bitcoin may become unreliable for an indefinite period of time. This means that any bitcoins you receive after that time can then then disappear from your wallet or be a bitcoin type that others will not accept payment.
When the situation is resolved, the validation point will automatically return to normal confidence or there will be two competing versions of Bitcoin (or more). In the previous case, you can return to using Bitcoin normally; In the latter case, you will need to take additional steps to start getting safely bitcoins.