Social media, email, and web browsers are first-party data collection parties. When you interact with these sites, information about your behavior is stored in the company’s proprietary databases; while you scroll Instagram, Instagram will note your scrolling and network behavior to curate the posts and advertisements on your feed. First-party data collectors can make money selling your data to third-parties; so even if the service is free, companies are able to profit from your activity on their website and personal information revealed through website interaction.
Below is a non-exhaustive list of how to protect your privacy and data while using first-party data collectors like social media, email, and other internet services.
Facebook Help page about privacy settings on Facebook.
Wired article from March 2018 about how to increase your privacy on Facebook using Facebook's privacy tools.
Regularly updated Lifewire guide to Facebook privacy.
Image Credit: https://commons.wikimedia.org/wiki/File:F_icon.svg
Instagram Help page about privacy settings on Instagram.
May 2019 Verge article about privacy on Instagram, including monitoring your account for potential hacks.
Regularly updated Lifewire guide to privacy on Instagram.
In addition to the concerns above, there are scammers on the internet that will attempt to exploit human psychology in order to get you to reveal sensitive personal information such as passwords. These "Phishing" scams are designed to steal your information so that bad actors on the internet can make money through fraudulent means. However, there are lots of resources available to help you avoid these scenarios.