These are like the Sainsbury's Online or the Ocado of the investment world.
Think of a platform a bit like an online supermarket. It's one online account where you can hold your shares, funds, ISAs and even a pension under a single roof. This one-stop shop makes the boring admin of your investments so much easier – one password, one account, one tax statement... you get the point!
These platforms are generally more transparent and lower-cost than the old-school financial products.
You need to get your head around the three main types of charge.
Of course it varies from place to place but as a rule of thumb expect to pay about £10-£12 all-in for every £1,000 you invest this way.
Read about passive funds for cheaper options or look for the lower-cost platforms in our Best Buys.
Our two-page guide explains these one-stop online investment shops in more detail.
Take me shopping...
Most platforms will let you buy funds, shares, exchange traded funds. And you can also decide whether to put these investments in a trading account, an ISA or a DIY pension referred to as a SIPP.
The other benefit of most investment platforms is that these days they have helpful tips and pointers for those of us who don't have the foggiest where to start or what to pick.
Most will have fund shortlists, and research analysts will have compiled their top picks. If this is still more choice than you want, many offer ready-made portfolios. A sort of Blue Peter here's-one-I-made-earlier.
Our Best Buys list shows you who we rate for less confident investors.
If you're a long-in-the-tooth investor and you just want the cheapest places to manage investments, look at the fixed fee guys Alliance Trust Savings and Interactive Investor if your portfolio is larger than £75,000 (ish). Or iWeb is very cheap... and looks like a platform from 1970s East Germany. But it's cheap!
Vanguard is a recent addition to the UK scene and a low-cost simple option if lots of investment choice is your idea of hell. It's your investment onesie.
Help me choose!!!?