Web hosting provider lock-in occurs when you become overly dependent on one provider, making it difficult to switch to another without incurring high costs or data loss. To avoid lock-in, choose hosting providers that use industry-standard technologies such as cPanel, MySQL, or WordPress. Ensure that your data is easily exportable and that you maintain control over your domain and website backups. Always read the fine print regarding renewal rates and contract terms. Lastly, monitor the flexibility of your hosting provider’s services, and avoid long-term contracts unless you're confident in their offerings.