Object storage appears inexpensive initially due to low storage costs, but unexpected high bills arise from egress charges, which are for data leaving the provider's network. Egress costs are incurred every time data is served to users, through CDN origin pulls, cross-region transfers, backup retrievals, and even failed downloads. These charges are not immediately apparent when storing data, making them a surprise on the first invoice. The true cost of object storage is a combination of storage fees and egress fees, with egress scaling based on usage rather than the amount stored. For example, a media site storing 100 GB but serving 2 TB in a month faces significant egress costs. High egress fees also act as a vendor lock-in, making it expensive to migrate data to another provider. Services offering zero-egress object storage, like Cloudflare R2 and Backblaze B2, eliminate this surprise cost by charging only for storage. Egress is a major concern for applications that frequently serve large files to many users, such as media sites or public asset hosting. However, for low-traffic internal tools or archives, egress costs are negligible. Understanding one's traffic patterns is crucial to assessing the impact of egress charges. Ultimately, storage costs are predictable, while egress costs are tied to how often and by how many users your files are accessed.