In recent times, what is user id has become increasingly relevant in various contexts. [GA4] User-ID - Analytics Help - Google Help. The User-ID feature lets you associate your own identifiers with individual users so you can connect their behavior across different sessions and on various devices and platforms. Measure activity across platforms with User-ID - Analytics Help. Analytics interprets each user ID as a separate user, which provides you with more accurate user counts and a more holistic story about a user's relationship with your business.
Equally important, find your YouTube user & channel IDs - Google Help. Each YouTube channel has a unique user ID and channel ID. These IDs are used to refer to the channel in certain apps and services. Find your channel's user ID & channel ID You can see your chann
利用 User-ID 評估跨平台活動 - Analytics (分析)說明. 每個 User-ID 的長度不得超過 256 個半形字元。 注意: 使用 User-ID 時,您有責任確保符合 Google Analytics 服務條款 的規範。 包括避免使用不允許存取的個人識別資訊,並在隱私權政策中明確指出您使用 ID 的情況。 User-ID 不得包含第三方可用於判斷使用者身分的資訊。 Building on this, [GA4] User-ID - アナリティクス ヘルプ. [GA4] User-ID User-ID 機能を使用すると、自社で生成したユーザー ID を個々のユーザーに関連付けることができるため、さまざまなセッション、デバイス、プラットフォームをまたいで各ユーザーの行動を把握できます。 Best practices to avoid sending Personally Identifiable Information .... User IDs Before using User IDs, read Best practices for User-ID Page URLs and titles The basic Analytics page tag collects the page URL and page title of each page that is viewed.

PII is often inadvertently sent in these URLs and titles. Both the URL path and parameters must be free of PII. If there is any possibility of your URLs, URL parameters, or titles containing PII, you'll need to ... [GA4] User explorer Explore segments of users and drill into individual user activities. User explorer lets you select specific groups of users, such as users who are engaged with your property on both your app and website, and drill down on each individual user's activities. About Analytics sessions - Analytics Help - Google Help.
To analyze different sessions outside of Google Analytics, consider joining the user_id or user_pseudo_id with the session_id to get a unique identifier for each session. From another angle, session number identifies the number of sessions that a user has started up to the current session, for example, a user's third or fifth session on your site. User id: Definition - Google Ads Help. A User id is a unique customer identifier by which an advertiser chooses to identify a user visiting their website. [GA4] BigQuery Export user-data schema - Analytics Help. Data tables When you export user data, Analytics creates two new tables in your BigQuery project: Pseudo ID Contains a row for every pseudonymous identifier.

Data for a user is updated when there is a change to one of the fields. Data for unconsented users is not exported to this table. It's important to note that, user IDs are not exported to this table. Last active timestamp is exported to this table.

📝 Summary
Understanding what is user id is important for individuals aiming to this field. The knowledge provided above works as a strong starting point for ongoing development.
