Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters. It is commonly used to embed images in HTML/CSS, transmit binary data over text-based protocols like email (MIME) or JSON APIs, and store binary data in text formats. Base64 increases data size by approximately 33%.

URL encoding (percent-encoding) replaces unsafe or reserved characters with a percent sign followed by two hex digits (e.g., space becomes %20). This ensures URLs are transmitted correctly over the internet. encodeURIComponent encodes individual parameters, while encodeURI encodes a full URL, preserving characters like :, /, and ?.

MD5 produces a 128-bit hash (32 hex chars) and is fast but considered cryptographically broken. SHA-1 produces a 160-bit hash (40 hex chars) and is also deprecated for security use. SHA-256 produces a 256-bit hash (64 hex chars) and is currently widely used for secure hashing. For data integrity checks, any of them work; for security-sensitive applications, use SHA-256 or SHA-512.

No. Base64 is an encoding scheme, not encryption. It does not provide any security or confidentiality. Anyone can decode Base64 data without a key. Base64 is used for data representation and transport, not for protecting sensitive information. If you need to protect data, use proper encryption algorithms like AES.

URLs can only contain a limited set of ASCII characters. Special characters (like spaces, Chinese characters, or symbols like & and =) have special meanings in URLs or are not allowed. URL encoding converts these characters into a safe format so they can be included in URLs without breaking the structure or being misinterpreted by web servers and browsers.