Great summary of sources to keep up to date with FinTech by Albert.
Another fantastic source is The Fintech Collective who have been cited alongside Finextra and Wall Street Technology before. Worth subscribing to their weekly newsletter that provides timely, authentic and expert-led insights here.
Basically, FinTech (a mashup of "financial technology") is any business that uses software to provide financial services. According to Wikipedia, "FinTech companies are generally startups founded with the purpose of disrupting incumbent financial systems and corporations that rely less on software." Now that we've got the definition pinned down, here is my personal list* of go-to resources I use to stay up to date in one of the fastest-growing industry currently existing: