Because of the web today, all online brokers invest heavily into account security. SSL websites (look for “https” at the beginning any URL) are used by most brokers and some are now even offering two-factor authentication (using your phone to confirm a code before logging in). Just like shopping online and choosing a trustworthy website to purchase from, the best bet is to choose a well-known, established broker for your portfolio.
The trading products you can purchase using these platforms can include stocks, commodities, derivatives, bonds etc. which can be traded between the traders on the stock market with intermediates such as investment banks, stock exchanges, brokers and market makers. A communication network is set-up between the various intermediates and the traders, which facilitates proper execution of the whole system.